Feature of the generic dominant. Reasons for the onset of labor

Examining the Causes of Weakness labor activity- one of the most difficult sections obstetric pathology - greatest development reached in recent decades. The weakness of labor activity was a problem of study for obstetricians of the past. But only with the creation of modern equipment that makes it possible to study the contraction of the uterus, and the deepening of knowledge on the biochemistry of the contractile function of muscle elements, this issue could receive some coverage.

An in-depth study of the causes of the weakness of labor activity is to a certain extent connected with the issues of labor anesthesia, which have become widespread in our country.

What is the reason for the weakness of labor activity, which manifests itself spontaneously in some women in labor or sometimes occurs after drug anesthesia for childbirth? In previous lectures, the conditions that develop in the body of a pregnant woman at the time of the onset of childbirth have already been analyzed.

Let us recall the preparatory mechanisms involved in the unleashing and regulation of labor activity. In the unleashing of the birth act, nervous and humoral factors are of primary importance. Preparatory processes in the nervous system consist in special relationships between the cerebral cortex and subcortical centers. These ratios boil down to the fact that towards the end, excitatory processes in the cerebral cortex decrease, and in the subcortical centers and the spinal cord they increase accordingly (Sechenov's phenomenon). At the same time, apparently, the peripheral parts of the nervous system, the receptor apparatus located in the uterus and other parts of the birth canal, become more sensitive to irritations. Preparation also takes place in other organs, which is reflected in the composition of the humoral environment. The latter consists in the fact that more acetylcholine, hormones (ovary, pituitary, adrenal glands, etc.), products of cell metabolism enter the bloodstream. Interacting with each other, they cause an increase in the biological activity of each of them separately.

This complex restructuring leads to a state of a certain readiness of the body for the onset of labor. The established level of readiness for childbirth by these same factors, apparently, is maintained throughout the entire birth act.

Does the unleashing and course of the birth act depend only on these factors?

How does this question appear in modern understanding? This preparation does not yet exhaust everything that actually happens in the body. This preparation is still not enough for the normal unleashing and course of childbirth.

The complex biological process that takes place in the uterus should also be taken into account; the state of its muscular elements and neuromuscular apparatus, the anatomical and physiological usefulness of the whole and its various parts, the functional relationship between the body (mainly the motor section) and the neck, as well as the state of individual sections of the birth canal.

Childbirth is a reflex process. As you already know from previous lectures, the uterus has a special arrangement of muscle fibers and innervation. These features are such that when the body contracts, there is a simultaneous relaxation and stretching of the neck. Such coordination of contraction and relaxation in different parts of one organ, in particular in the uterus, is called a reciprocal reaction. The center of reciprocal reactions is located in the cerebral cortex, but only its reflection takes place in the uterus or in another organ. There are many such reciprocal relationships (reactions) in the body. Take, for example, flexion and extension of the limbs. It would be impossible to bend an arm or leg if there was no coordination of the reaction of the flexors and extensors, or, for example, the release of bile from the gallbladder. At the moment of contraction of the muscles of the bladder, its sphincter, on the contrary, relaxes. Therefore, for the implementation of such a complex reaction, it is necessary to have a certain state in the entire chain: the cerebral cortex, pathways, peripheral neuromuscular apparatus, muscle. It is often possible to observe the course of childbirth when, in the body as a whole, the readiness for unleashing them and the correct course, apparently, has come, but they proceed incorrectly due to features that are directly related to the uterus. You should know that although the human uterus is an unpaired organ, it is embryologically composed of two merged Müllerian canals. Therefore, it is possible various options developmental defect. In one case, the defect can be expressed noticeably, anatomically (infantilism, hypoplasia, bicornuity, etc.), in the other, the uterus appears to be anatomically normal, and its inferiority manifests itself in functional insufficiency. This insufficiency refers to the entire uterus as a whole or to any part of it: the upper section, the cervix, the left or right half. The functional ability of the uterus can be disturbed by conditions associated with the painful course of pregnancy (toxicosis), which were in the past inflammatory processes, the presence of a tumor (fibromyoma), its excessive stretching (polyhydramnios, multiple pregnancy, large fruit), beriberi, as well as violations of biochemical processes in the muscular elements of the uterus.

Childbirth is an ancient natural process in which a baby is born. Every woman in this magic time a generic dominant appears, or a special state of the nervous system that helps with childbirth. From a physiological point of view, it triggers the birth of a child.

On last week During pregnancy, the body is rebuilt so that the birth of the baby goes well. Easy childbirth without complications is possible only when future mom fully prepared for the process physically and psychologically.

The generic dominant is a state of the central nervous system that helps to bring to the fore the main reflexes responsible for labor activity. Thus, the body prepares for a difficult physiological process.

At this time, the feeling of fear is dulled, the woman feels calm and ready for the appearance of the baby. It is necessary to maintain the tribal dominant and trust it. She is able to anesthetize childbirth, suggest the right position and correct technique breathing.

Being in the hospital, experts advise to keep inner peace, focus on your feelings and the unborn child.

The dominant makes the first meeting with the baby unforgettable and bright. The feeling of euphoria does not leave mothers for 7-9 days after childbirth.

It is difficult to say what causes the onset of childbirth exist. It's so difficult process that scientists have not figured it out to the end. In the aggregate, the causes are considered to be an increase in the work of nerve stimuli, an increase in the content of hormones in the blood, and a decrease in the level of melatonin.

What influences the development of labor

Each theory of the origin of labor activity comes down to the fact that the time comes for the fetus to part with the uterus, and the generic dominant and precursors start the process of “pushing out”. According to one version, the reason for the start of the process is the growth of antibodies, leading to relaxation of the uterus. Other scientists believe that contractions are caused by the placenta, in which special substances appear.

One way or another, how did most women go into labor?

1. frequent contractions appear, preparing the uterus and baby for birth;
2. amniotic fluid leaves, starting labor.

These are the two most common reasons for the development of labor activity. By medical indications the process is started by applying medical preparations or omniotomy - a mechanical puncture of the bladder.

Levels of regulation of labor activity pass through the nervous system and humoral pathways. In the process of childbirth, the involvement of receptors plays an important role. Under their action, the uterus contracts, starting the process. Central nervous system primarily responsible for the regulation of the process.

Harbingers

During this period, special signs appear that indicate that the body is preparing for childbirth. From the point of view of psychology, the birth process starts when female body comes under the influence generic dominant. It is she who will become the support and support of a pregnant woman in the perinatal period.

Harbingers appear in the last week of gestation and are as follows:

• the fruit ripens amniotic fluid decreases;
• “training contractions” appear - irregular and short. They will provide normal course childbirth and prepare the uterus;
• it will become easier for a pregnant girl to breathe, as the fetus descends;
• the child will be less mobile;
• discharge of the "cork" - brownish mucus.

Can contractions start suddenly? Very rarely, the birth process begins suddenly, without precursors. But premature birth that occur before 37 weeks of gestation may begin suddenly. In this case, you must immediately call ambulance and go to the hospital.

Periods

The reason for the onset of labor is the prenatal preparation of the body. It starts three weeks before the baby arrives. At this time, the generic dominant is formed and becomes brighter. In the future, she will facilitate contractions, give a woman peace of mind and confidence at the right time.

Why do some give birth easily while others are difficult? How the process works depends on physiological features organism, as well as on how the dominant developed in a pregnant girl. In order for it to form, you need to walk a lot or do any kind of creativity.

The stage of cervical dilatation is important for the birth of a child. Due to contractions, the neck shortens, becomes thinner. This period is the longest and quite painful.

Then comes the pushing stage. The head of the child presses on the bottom of the pelvis, the abdominal muscles contract. The period ends with the birth of a child. There are easy and difficult births, it depends on the preparation of the woman, the physiology of her body, and proper breathing.

Completes the postpartum period. Namely, separation of the placenta, contraction of the uterus. In the presence of ruptures, the obstetrician sutures. Mother and baby are transferred to postpartum department where they will spend some more time under the supervision of doctors.

Danger of childbirth for mother and baby

natural childbirth risk for both mother and child. Wherein, C-section not recommended for pregnant women without a strong indication.

Why is childbirth dangerous?

• high risk of intracerebral bleeding in the fetus;
• dangerous premature detachment placenta;
• the child may experience asphyxia, that is, a lack of oxygen;
• the baby may be injured during delivery. This is especially true when things are moving fast.

The consequences cannot be predicted in advance. Natural childbirth is the most favorable process for the birth of a baby.

In order for the birth to go well, and the joy of motherhood to overwhelm the woman, one must not forget about the support and development of the generic dominant. Experts advise young mothers to be creative, walk a lot, enjoy life. This, from a psychological point of view, will help prepare for the birth of a child.

The use of antispasmodic, anticholinergic and adreno-blocking agents in parturient women with later forms late toxicosis in order to regulate labor activity is due to the fact that the violation of the motor function of the uterus in pregnant women and women in labor with late toxicosis is causally associated with a number of mediator systems. Thus, the role of this system in the pathology of the contractile function of the uterus, the state of intrauterine fetuses in normal and hypoxia in parturient women with late toxicosis of pregnant women has not been sufficiently studied so far. As you know, with toxicosis of the second half of pregnancy, complications such as premature birth, untimely discharge of water, etc. are observed in a greater number (E. S. Esterin, 1957, D. A. Govorov, 1965, G. G. Khechiiashvili, 1974, 1977 and others). A number of anomalies of labor activity ^ can be caused by disturbances in the state of the adrenergic and cholinergic systems: the release of norepinephrine and adrenaline, the content of acetylcholine and cholinesterase. These issues are reflected in a number of studies by domestic scientists (A. Ya. Bratushchik et al., 1969, M. A. Petrov-Maslakov, L. G. Sotnikova, ON. Arzhanova, 1979, etc.). In the work of S. I. Tregub, it was shown that with edema of pregnant women, the content of adrenaline was the same as in healthy pregnant women, and the content of norepinephrine was significantly lower. With nephropathy, the content of adrenaline was higher than in healthy pregnant women: 14.*^ mig ± 3.1 versus 9.0 ± 2.9 mcg in the norm; 0 ± 3.1 m "kg is normal. In the studies of O. N. Arzhanova (1979), the functional state of the catecholaminerpic system was determined both in blood plasma by the shektrofluorimetric method modified by E. Sh. Matlina (1965) and V. G. Chaliapina (1969) and in the daily amount of urine by the same method using spectrofluorimeter MRF-2 A from Hitachi. Interesting regularities are revealed. Thus, during a physiologically occurring pregnancy, the content of adrenaline and norepinephrine in the blood plasma and in the urine does not differ significantly from that in healthy non-pregnant women. The content of catecholamines in plasma increases two-fold during childbirth, sharply decreases in early postpartum period, and then quickly recovers by the second day after birth. These data indicate the normal function of the peripheral-adrenal system in healthy women during pregnancy, childbirth and the postpartum "period. This is probably due" to the fact that during pregnancy, as shown by extensive ex-scientific studies by Sjoberg (1978) on guinea pigs, as well as Thorbert's (1979) study of human adrenergic innervation. Thorbert et al. P979) have been identified, on the one hand

rona that in an empty horn during unilateral pregnancy there are few functioning adrenergic nerves, but there is no degeneration. At the same time, a decrease in norepinephrine was found in the cervix at the end of pregnancy, which indicates an increase in neutral activity. Sjoberg (1979) showed that by the end of pregnancy there is an almost complete disappearance of the adrenergic nerves of the skein. The author believes that: pregnancy causes a decrease in the level of norepinephrine in the macaque as a result of a neurobiological process, with degeneration of the terminal nerves. A study by J. Burnstock and M. Costa (1979) showed that all peripheral adrenergic neurons are sympathetic postganglionic cells and all of them have cholinergic excitatory inputs to their CNS, and some of them have inputs from internal organs. Currently, data have been obtained on the presence of inhibitory adrenergic input of intraganglionic origin in some ganglia. D. E. Alpern (1963) proved that there is a mutually correcting relationship between adrenergic and hyulinergic mechanisms. At the same time, increased release of adrenaline or norepinephrine stimulates the release of acetylcholine, as is believed, due to a decrease in the activity of cholinsterase. So, according to M. A. Petrov a-Maslakov et al. it is not possible to trace such a pattern in most pregnant women. These data are of significant interest for the obstetric clinic, since in recent years, ayarenergic substances have been increasingly used in the treatment of late toxicosis (I. I. Freidlin, 1966, S. G. Aliev, 1967, L. D. Spirina, 1970 , I. V. Borodai, 1970, V. N. Gorovenko, 1975). For clarity, the above-"th judgments are given modern scheme main pathways of sympathetic innervation of organs with additions by O. M. Avakyan (1977). The axons of ganglion nerve cells innervate the heart, smooth muscles of blood vessels and internal organs, intramural ganglia and glands. These axons form “long” postganglionic ionic sympathetic nerves. In addition, there are “short” postganglionic sympathetic nerve fibers that originate from cells that form ganglia directly at the organs of the small pelvis-uterus, etc. (Sjostrand 1965 and others.) . According to O. M. Avakyan (1977), “long” and “short” adrenergic nerve fibers are not an obligatory part of the peripheral sympathetic nerves, since according to at least for two organs, other types of innervation have been established: adrenal glands and sweat glands.

7.1. Regulation of labor activity by antispasmodic and osodinolytic agents

In modern obstetrics, the central problem remains the regulation of labor, since the prevention of pa-

tyulugic course of childbirth significantly reduces perinatal mortality. Implementation in medical practice new drugs with antispasmodic action has significantly expanded the "opportunities of practitioners in the treatment of labor anomalies and in violation of the contractile activity of the uterus in parturient women with late toxicosis of pregnant women, as well as in order to prepare high-risk pregnant women in the absence of biological readiness for childbirth, which to a certain extent made it possible to solve the problem of smooth muscle tone of semolina. Currently, a number of regular changes in physiological and biochemical parameters have been established when smooth muscles relax under the influence of antispasmodics: an increase in membrane potential observed simultaneously with inhibition of quince intoxication or caused by peak activity, a decrease in oxygen consumption smooth muscles and the content of ATP in them, an increase in the concentration of ADP., AMP and 1 cyclic 3.5 - AMP. From the above brief data, it can be seen that the introduction of new effective antispasmodics, as well as their combinations and knowledge of the features of their action, can help the doctor in choosing an antispasmodic if it is necessary to use it either in conjunction with other drugs of oxytocytic action, or in conditions of a pathological course of childbirth when the biochemical and biophysical parameters of body tissues can be so changed that they can "prevent the manifestation of the relaxing effect" of individual antispasmodics. The use of antispasmodic drugs in the complicated course of pregnancy and childbirth with their systematic administration will help to shorten the duration of labor, prevent and treat anomalies of labor, especially such disorders of contractile function, where there is an increase in basal or basic uterine tone. These measures can reduce birth trauma of the soft birth canal, as well as injuries fetus and newborn. It is also important to use the combined use of central and peripheral n-cholialytics (antispasmodics), especially in the case of primary weakness of labor activity. It is important to use such combinations in the clinical practice of an obstetrician-gynecologist, since with the help of various pharmacological agents it is possible to control the processes 1 that occur in the ganglia, which is a powerful means of controlling many essential functions myometrium. Another thing is also important in this connection: the absence of a barrier similar to the tematoencephalic one makes ganglion neurons much more accessible to various substances introduced into the blood than neurons of the central nervous system. For obstetric practice, it is also important that the holipositive effect of some antispasmodics (gangle-

■ron, quateron, etc.). In this case, this effect manifests itself on | | (the level of postgangular cholinergic synapses. S

I Clinical and pharmacological "characteristics of ^spasmolytics I

I Spazmolitin (difacil, trazentin) belongs to the group! Icentral anticholinergic substances, as it has a pronounced effect on the central cholinergic synapses .;!

■ Central anticholinergics enhance the effect of neurotropic E

■ and analgesics, and also render, in contrast to |

■ m-cholinolytics, for higher nervous activity facilitating effect in the form of strengthening excitatory and inhibitory I

■ processes, normalization of higher nervous activity. Spaz-E

■ Mulitsch has relatively little atropino<подобнюй " I активностью-1/20 атропина. Поэтому в терапевтических до-Изах он не оказывает влияния на величину зрачка, слюнную

I secretion and heart rate. For obstetric practice, it is important, in the regulation of "labor activity," that "a large role in the antispasmodic effects of the drug is played by its M" IOTRO "Pnee action, expressed no worse than that of papave- | riyaa, in connection with which sp "azmolitin is used in the clinic as 1 universal antispasmodic effect in various pathological conditions of internal organs. I Antispasmodic has a blocking effect of Sha vegetative 1 ganglia, the adrenal medulla and the pituitary adrenal 1 system. Taking an antispasmodic at a dose of 100 mg orally improves 1: the conditioned reflex activity of a person, as spasmo-1 lithium primarily has an effect on n-cholinergic structures 1 of subcortical formations. active structures and systems of the brain, especially the reticular formation, as well as the cerebral cortex, prevents overexcitation and exhaustion of the central nervous system and thereby m most prevents shock conditions. Spasmolitin in the genus can be used at a dose of 100 - 200 mg odaomratigo, orally E at intervals of 2 - 3 hours between doses. Total dose! during childbirth should not exceed 1 Mir 600 inside. 1

Gangleron. The drug has a ganglioblocking, central anticholinergic, antispasmodic and anesthetic action. Gangleron is a persistent substance that is slowly hydrolyzed in the body. The drug dilates blood vessels, causing a moderate hypotensive effect. In diseases of the cardiovascular system in parturients, gangleron at a dose of 1-3 mg/kg of body weight significantly suppresses reflexes from the heart, normalizes pathological changes in the electrocardiogram, || normalizes and improves myocardial nutrition, which also occurs in parturient women with severe forms of late toxicosis, reduces the flow of vasoconstrictive impulses to the coronary

vessels. In addition, gavdieron at a dose of 0.5–1 mg/kg provides a gradual increase in the oxygen content in arterial blood after 20–30 minutes, and at the same time there is a significant, but short-term increase in the oxygen content in the venous blood and an increase in the volume and oxygen content. and an increase in the volumetric velocity of venous blood flow. Arterial pressure decreases gradually, decreasing by 15 - 20 mm Hg. Art. after 60 min. after administration of the drug at a dose of 2 - 3 mg / kg. With an increase in the dose of gangleron to 2-5 mg / kg, there is a significant increase in the oxygen content in the blood by 30-70% compared with the initial level, which is of great importance for fetuses in mothers with late toxicosis with symptoms of chronic fetal hypoxia. Therefore, simultaneously with the antispasmodic effect, it is possible to achieve an improvement in the state of the fetus (V. V. Abramchenko, 1967) according to phonocardiography after the administration of gangleron. It has been established experimentally and in the clinic that gangleron has a stimulating effect on the uterus. In this case, gangleron blocks the conduction of impulses in the parasympathetic ganglia. The holinopositive action of gangleron is very significant. A single single dose of gangleron 30-90 mg (1.5% solution-4-6 ml) intramuscularly or intravenously in 20 ml of 40% glucose solution.

Halidor-antispasmodic of myot^opnogo action. Halidor is a drug that is many times more effective than papaverine in terms of antispasmodic and peripheral vasodilating effects. The drug has a tranquilizing and local anesthetic effect. It is significant to note that halidor is a low-toxic substance and causes only sometimes minor side effects. It has been established that halidor is less toxic than papaverine for all types of administration. The teratogenic effect of halidor has been studied in a variety of animals and it has been shown that even with the introduction of very high doses of the drug from the very beginning of pregnancy, no teratogenic effect of the substance was detected. The drug has a direct myotropic effect and at a concentration 2-6 times lower than papaverine relieves spastic contractions of the myometrium caused by oxytocin.

Halidor at a dose of 1-10 mg/kg of body weight temporarily lowers blood pressure, but to a lesser extent and for a shorter duration than papaverine. The drug expression increases coronary circulation and reduces coronary vascular resistance. It was revealed that in clinical conditions, a significant peripheral vasodilating effect of halidor is revealed, which is of great importance in women in labor with late: toxicosis, in "■ which disturbed vascular tone and microcirculation. Halidor has a preventive effect on peripheral vascular spasm under conditions of narcotics.

■ chesky circulation that provides normal fabric I an exchange.

I Galidor can be used in parturient women with combined

■ late toxicosis with cardiovascular diseases, so sh how the drug has a sharp increase in the utilization of oxygen-I kind by the myocardium and a change in the ratio of the concentration of oxidized and reduced forms of I in the direction of accumulation in myo-1; card of restored forms. For obstetric practice, the most important is the visceral antispasmodic effect of halidor. It has been established that halidor at a dose of 50–100 mg I intravenously in a spastic state of the uterine os leads to a shortening of the duration of the period of disclosure and the period of i expulsion. Absolute contraindications to Halidor is not available for use Side effects are very rare and safe There are reports of the possibility of the drug to cause dizziness, nausea, headache, dry mouth and throat, drowsiness Dosage: 1 tablet contains 100 mg of halidor, 1 ampoule (2 ml of standard solution ) contains 50 mg of the drug.It is recommended to administer the drug orally at a dose of 1-2 tablets (100-200 mg, orally) or 4 ml (100 mg), intravenously with 20 ml of 40% glucose solution, intravenously, slowly. the recommended total dose of halidor is 300-400 mg at intervals of 2-3 hours.

Spasmoanalgesic - baralgin

The composition of the drug contains three active ingredients: analgesic, antispasmodic and parasympathomimetic. As you know, the pathological processes occurring in the human body are often accompanied by spasms of smooth muscles, especially with an excess content of acetylcholine, which can be observed in some forms of labor anomalies. Therefore, all processes associated with increased smooth muscle tone can be controlled with anticholinergic substances. In practice, not all anticholinergic substances are used as antispasmodics. The fact is that in addition to the antispasmodic action, anticholinergic substances also affect the function of the heart, sweat, salivary glands, etc., which in some cases is undesirable.

Baralgin "consists of neurotropic, myotropic and analgesic components. The first component acts like papaverine and therefore it is classified as a group of myotropic antispasmodics with a stable effect. It is absorbed directly by smooth muscle cells, and this leads to the fact that it stops spasms smooth muscles, regardless of the innervation of organs.In addition to a pronounced myotropic effect, this substance also has some milder neurotropic

(parasympatholytic) and antihistamine action. As a result of this property alone, it is possible to obtain a neuromyotropic antispasmodic effect. The second component is a typical representative of neurotropic antispasmodics, which act like atropine, but without its side effects. The parasympatholytic effect of this substance is due to the blockade of the transmission of impulses to the peripheral nerve endings of smooth muscles. It also acts as a vagotropic ganglioplegic with blockade of the parasympathetic ganglia. The third component is a strong central analgesic that relieves pain of various origins and, in spastic conditions, helps to increase the effect produced by the antispasmodic components of baralgin.

Due to its own myotropic action, this substance is a synergist of the first component. Thus, the advantages of baralgin can be formulated as follows: a carefully selected combination of antispasmodics with a neurotropic myotropic effect and a potent central analgesic opens up wide opportunities for use in obstetric practice. The synergistic effect of the individual components allows you to reduce the dose and thereby reduce the side effects of both atropine and papaverine. The drug is a strong antispasmodic and analgesic without narcotic action, the toxicity of the drug is minimized, since, first of all, the pyrazolone component does not cause side effects. The value of the drug is also that it can be used intravenously, intramuscularly, orally, in suppositories. In obstetric practice, baralgin is increasingly used to accelerate labor and regulate labor, as well as prepare the cervix for childbirth in the absence of biological readiness for childbirth, with pelvic presentation of the fetus, with various forms of late toxicosis.

How to use baralgin: intramuscularly or intravenously, 5 ml of a standard solution, repeated administration during childbirth is recommended after 2-3 hours. With intravenous administration of baralgin, the action begins immediately, with intramuscular administration after 20-30 minutes (V. V. Abramchenko, E. A. Lantsev, V. V. Morozov, M. V. Kutalia-Izoria, 1978).

Fentanyl- a derivative of piperidine, but in terms of the strength of the analgesic effect, it surpasses morphine by 200, and promedol by 500 times. The depressant effect on respiration in fentanyl develops in parallel with the analgesic, but is less pronounced compared to the substances of this group. Fentanyl has a selective blockade of some adrenergic structures, which is important in parturient women with late toxicosis, as a result of which, after its administration, the reaction to catecholamines decreases. Ras-

The fall of fentanyl occurs quite quickly with the participation of liver enzymes. A reliable antidote is narorphy. Droperidol is one of the effective antispasmodics! from the group of neuroleptic drugs, especially in combination with fentanyl. It has been established that droperidol causes a moderate adrenergic blockade, spreading mainly to a-adrenergic receptors. This action of droperidol | underlies the hemodynamic effects: vasodilation, | a decrease in peripheral resistance and moderate arterial hypotension. It has an antispasmodic, sedative effect, potentiates the action of narcotic, analgesic drugs, has an anti-shock and antiemetic effect. Dosage of drugs in childbirth: droperidol - 5 - 10 mg (2 - 4 ml) and fentanyl - 0.1-0.2 (2 - 4 ml) intramuscularly in one syringe. The average single dose of droperidol is equal to 0,1 -0.15 mg / kg body weight of the woman in labor, and fentanyl - 0,001 - 0.003 mg/kg.

Treatment of the pathological preliminary period

in pregnant women with late toxicosis - as a way to prevent abnormalities of labor

As shown by our studies on the study of the motor function of the uterus in pregnant women with late toxicosis, especially in its severe forms, there are a number of violations of the contractile function of the uterus. It is important to note that the pathological type of uterine contractions, which is established shortly before childbirth, also occurs at the beginning of labor. That is why, in the presence of a pathological preliminary period in this contingent of pregnant women, it is increased. uterine activity is expedient for the prevention of labor anomalies and other complications, we have developed a treatment method for the use of diazepam (seduct hay, relanium, valium, tazepam). Diazepam, as shown by pharmacological and electrophysiological studies, acts through the limbic region, which, according to modern concepts, is responsible for the regulation and unleashing of labor. Diazepam must be administered at a dose of 20 mg / 4 ml of the standard solution) intravenously, slowly in 20 ml of sterile saline at the rate of 1 ml of the drug for 1 minute, in order to avoid the occurrence of diplopia or slight dizziness that occurs with the rapid administration of the drug. A dose of 20 mg of seduxen is recommended as optimal and at the same time not giving side effects. After the introduction of the drug, on average, after 6-8 hours, regular labor activity is established, which ends with spontaneous labor. Hysterographic studies show that contractions become more regular after the administration of Seduxen.

and instead of small uterine contractions of the Alvare type, large uterine contractions of the Braxton-Gix type appear, which contribute to the faster maturation of the cervix in pregnant women with late toxicosis, and uterine contractions begin to predominate more in the bottom and body, i.e., begins to manifest itself in more observations of the so-called "triple downward gradient" of uterine contractions, characteristic of the physiological course of childbirth. At the same time, the intensity of uterine contractions clearly begins to increase, despite the fact that the duration of the pauses between uterine contractions begins to lengthen, there is also a decrease in the increased basal (basic) uterine tone by 6–8 mm Hg. Art. Normalization of the contractile function of the uterus is due to a decrease in mental stress, fear, there is a normalization of the central structures located in the limbic region and thereby the regulation of the contractile activity of the myometrium. In addition, there was a change in the excitability of the myometrium according to the oxytocin test after the administration of diazepam. This increase in the oxytocin test after the administration of the drug is obviously due to the fact that diazepam may also have another mechanism of normalizing action on the myometrium, i.e., it increases the sensitivity of the oxytocin zones that are present in the limbic region and which change the reactivity of the myometrium. Simultaneously with diazepam in pregnant women with late toxicosis and lack of biological readiness for childbirth, especially if early delivery is due, it is necessary to prescribe antispasmodics of central and peripheral action: an antispasmodic at a dose of 100-200 mg orally and a solution of hach-! Gleron - 30 - 60 mg (1.5% solution 2 - 4 ml) in combination with 20 ml of 40% glucose solution intravenously. In order to create a hormonal background, it is necessary to introduce 20,000 units of folliculin 2 times a day with an interval of 12 hours. The colpocytological studies carried out by us (V. V. Abramchenko et al., 1978) in late toxicosis by the method of luminescent colpocytology made it possible to establish that in late toxicosis, colpocytological patterns are heterogeneous, but “dystrophic” smears are the most alarming in prognostic terms. The colpocytological method is considered an objective test for assessing the function of the placenta in late toxicosis and there are three stages of changes in the colpocytological picture:

Stage 1 - initial - minor violations of the progesterone effect, when colpocytograms did not go beyond the norm, stage 2 - severe placental insufficiency, there is a premature release of cytograms into the state "shortly before delivery" and "duration", and stage 3 - final - when the strokes corresponded to the pictures you

Significant destruction of squamous epithelium. Studying colpocytb-Vramma with pure forms of late toxicosis of pregnant women, we distinguish two groups according to the duration of pregnancy: 32-36 non-Kel and 37-41 weeks. Such a division is due to those who, from the 37th week of pregnancy, normally begin the endocrine preparation of the woman's body for childbirth. In each group, it is necessary to distinguish 3 groups:

SCH I - hormonal saturation corresponds to the actual gestational age.

| II - an increase in the level of estrogen relative to the norm for 1 given period of pregnancy.

I III - a decrease in the level of estrogen relative to the norm for the expected gestational age. It is necessary to carry out these changes in each group in relation to strict saturation, taking into account the severity and duration of late toxicosis.

It was established that at any gestational age and a non-prolonged monosymptomatic course of late toxicosis (edema of pregnant women, hypertension in pregnant women), the smear reaction corresponded to the actual gestational age. At a gestational age of 32-36 weeks, in the presence of a pronounced (nephropathy I-III degree), but not a long-term toxicosis (no more than 2-3 weeks), the second group smears are most common, the smear reaction rises to 3 and even 3-4. With a pronounced, long-term course of late toxicosis (over 3 weeks), as a rule, there was a decrease in the level of estrogens, relative to the norm for a given gestational age (group 3), with the development of degenerative changes in the squamous epithelium. With a gestational age of 37-41 weeks, with pronounced degrees of toxicosis, smears of the 3rd group were most common, which is explained by the presence of a large number of cases with a long course of late toxicosis. There are no clearly established reasons for such changes in vaginal smears with late toxicosis, but it can be assumed that the short-term, pathological effect of pronounced late toxicosis on the function of the placenta leads to the normalization of compensatory capabilities, i.e., to an increase in endocrine function, and, accordingly, to a large release estrogens, both by the placenta and the adrenal glands of the fetus. With prolonged exposure to late toxicosis on the function of the placenta, early aging of the placenta develops with a decrease in its endocrine function, and hence the suffering of the fetus.

At night, if after the introduction of estrogens and diazepam, uterine contractions disturb the pregnant woman and disrupt the rhythm of sleep-rest, it is advisable to repeat 20 mg of diazepam in combination with 50 mg of pipolfen and 40 mg of promedol solution. If within the next hour

after the introduction of these drugs, the pregnant woman cannot fall asleep due to uterine contractions, then she is prescribed the steroid drug ^viadryl G in the form of a 2.5% solution intravenously, quickly, in the amount of 1000 mg per 20 ml of a 40% solution of glucose. In order to prevent possible irritation of the punctured vein, 5 ml of a 0.5% solution of novocaine is injected before the injection of Viadril. In the future, after awakening, as a rule, labor activity either completely stops for several days or regular uterine activity occurs.

Regulation of labor activity with weakness of labor activity

As already noted, in women in labor with severe forms of late toxicosis, the number of anomalies in labor activity increases, requiring the appointment of labor-stimulating agents. At the same time, in the decisions of the XII All-Union Congress of Obstetricians and Gynecologists (L. S. Persianinov), it is considered that one of the most effective drugs is oxytocin, which must be prescribed With mandatory use of antispasmodics in established labor. With discoordinated labor activity, manifested mainly by asynchronous uterine contractions, pipertonus of the lower uterine segment and other symptoms, antispasmodic and analgesic drugs should be used more widely, taking into account the peculiarities of the effect of pharmacological substances on the fetus.

The use of antispasmodics in case of weakness of labor, both separately and in the foyer of the use of labor-stimulating agents, leads to a shortening of the duration of labor in primiparous and multiparous, respectively, by 3 hours. We consider it expedient to use the proposal of T. A. Starostina (1977) on the possibility of isolating

3 forms of this anomaly of generic forces, depending on the severity of it and the duration of childbirth.

I - primary weakness of labor activity of a mild degree (duration of labor up to 19 hours).

II - primary weakness of labor activity of moderate severity (duration of labor 19 - 24 hours).

III - severe (persistent) primary weakness of labor activity (duration of labor more than 24 hours).

When using antispasmodics with primary weakness of labor activity, the most pronounced antispasmodic effect from the use of spasmolytin is observed with a preserved cervix and with the opening of the uterine pharynx by 2–3 cm.

4 cm and more did not reveal a more pronounced antispasmodic effect.

With the combined use of spasmolitin and gangleron solution in the above doses, it also leads to a shortening (duration of labor by 1 hour in primiparas. In multiparous women, on the contrary, this combination of substances leads to a prolongation of the labor act also by an hour compared with the use of spasmolitin alone. Therefore, in multiparous women, a more pronounced labor-accelerating effect of the combination of spasmolitin and gangleron was not revealed, and this combination of substances can be used for the rapid opening of the uterine os in multiparous women.

The use of a gangleron solution with a preserved but immature cervix, or a maturing uterus does not lead to an antispasmodic effect. In the presence of a mature cervix, gangleron solution has a pronounced antispasmodic effect, both with a preserved and shortened cervix. When using the gangleron solution, when opening the uterine os by 2–4 cm, there is no more pronounced antispasmodic effect.

The use of halidor solution at a dose of 50 - 100 mg, intravenously with 20 ml of 40% glucose solution in women in labor with weakness of labor revealed the most pronounced antispasmodic effect in both primiparous and multiparous. It is recommended to take into account the fact that the use of halidor has a pronounced antispasmodic effect at various degrees of opening of the uterine os, starting from the preserved cervix in primiparas. In multiparous women, the highest antispasmodic effect was noted in the presence of a preserved cervix.

Regulation of discoordinated labor activity

The greatest difficulties in the practice of an obstetrician are women in labor who have a protracted course of the birth act due to "discoordinated labor activity. Discoordination of labor activity is one of the dangerous pathological conditions for both the mother and the fetus that occur during the birth act. Causes The occurrence of discoordinated labor activity has been studied and is still not enough.Discoordination of labor activity is clinically most often expressed in the absence or significant slowdown in the opening of a spasmodic uterine os or lower segment of the uterus, despite the regular nature of uterine contractions.Characteristic clinical symptoms of discordant labor activity are: 1 - painful, strong, sometimes weak contractions ("uterine rheumatism" in the terminology of old authors); 2 - a sharp slowdown in the opening of the uterine os; 3 - constant pain in the region, mainly of the lower back, as well as in the lower abdomen; 4 - lack of pro-

movements of the presenting part with normal ratios between the sizes of the pelvis and head; 5 - lack of coordinated uterine contractions between the bottom, body and lower segment of the uterus with a violation of the triple downward gradient of uterine contractions; 6 - early appearance of water stained with meconium, with the intensity of water staining as the intensity of discoordination increases, followed by the addition of pathological changes on the cardiotocogram of the type dip I or dip II.

With discoordination of birth fir trees, one of the leading clinical symptoms is significant pain in the lumbar region and sacrum, which disturbs the woman in labor and in the intervals between contractions, while the intensity of pain often does not correspond to the strength of uterine contractions. Therefore, in this contingent of women in labor, it is recommended, along with the antispasmodic effect, to also achieve adequate protection against pain trauma. It should be emphasized that the use of myotropic antispasmodics (spasmolythia, no-shpa, halidor), as well as antispasmodic analgesics (promedol, morphine), anticholinergics (gangleron, pentamin, kvateron) is most effective in women in labor with late toxicosis in combination with weakness of labor activities. However, these substances in the discoordination of labor activity give a short-term effect.

The highest antispasmodic effect in discoordinated labor activity in terms of regulation of uterine contractions, obtaining a central analgesic effect was obtained using the spasmoanalgesic baralgin, as well as long-term epidural analgesia according to the method developed at the Research Institute of AG. D. O. Otta RAMS \ (E. A. Lantsev et al., 1978).

The use of baralgin in discoordinated labor activity leads to a shortening of the duration of labor by an average of 4 hours. The duration of the second and third stages of labor remain unchanged. It is recommended that the following features be taken into account when determining the indications and time for the introduction of baralgin. In primiparas, a high antispasmodic and normalizing effect on the contractile function of the uterus was noted with a preserved and mature cervix. With the revealed protracted course of the birth act, due to the discoordination of the birth forces, in primiparas, it is most advisable to use the drug when the uterine os opens by 4 cm or more. At the same time, the average duration of labor after the use of baralgin with the opening of the uterine os by 5–6 cm did not exceed 12 hours, and with the disclosure of the uterine os by 7 cm or more, it did not exceed 5–6 hours. According to our hysterographic studies, baralgin leads to a decrease in basal tone by 5 ~ 6 mm Hg. Art., increase the intensity of uterine contractions And increasing the duration of the fight.

Regulation with excessive labor activity

In order to regulate labor activity in case of excessive labor activity, it is recommended to use a combination of neurotropic agents (chlorpromazine or propazine at a dose of 25 mg) in combination with a solution of promedol - 40 mg and pipolfen - 50 mg, intramuscularly, and if there is no effect, ether anesthesia is additionally applied within 1 - 2 hours.

A high regulatory effect is given by the use of inhalations of halothane at a concentration of 1.5 - 2 vol% (M. A. Petrov-Masla-kov, V. V. Abramchenko, 1977). At the same time, the use of halothane leads literally in the first 2-5 minutes, especially in parturient women with hypertensive forms of late toxicosis, to the normalization of labor activity, and when giving fluorotane over 2 vol%, a complete stop of labor activity. At the same time, the normalization of the fetal heartbeat is also noted. However, it should be noted that halothane inhalation in case of excessive labor activity is not an etiopathogenetic factor in the treatment of excessive labor activity. If the cause of excessive labor activity has not been eliminated, and also if the inhalation of ftorotane lasts less than 20-30 minutes, then after the termination of inhalation of ftorotane, excessive labor activity may reappear.

In recent years, there have been isolated reports of the successful regulation of labor activity with beta-mimetic drugs (partusisten, yutopar, ritodrin, brikanil, etc. (V. V. Abramchenko, N. I. Dontsov, 1979).

In conclusion, it should be emphasized that the differentiated use of antispasmodic drugs in late toxicosis of pregnant women, taking into account the type of anomaly of labor forces, the time of administration of the drug, the degree of opening of the uterine os, the dose and method of administration of substances, leads to a shortening of the duration of labor in both primiparous and multiparous on average for 3-4 hours. The combined use of central and peripheral n-anticholinergics (spasmolytin and gangleron) in the above dosages is recommended for the purpose of corrective action on the contractile function of the uterus in the body and lower segment of the uterus. The use of the antispasmodic halidor is most indicated in women in labor with a hypodynamic form of weakness of labor, since the drug leads to an increase in the intensity and an increase in the frequency of contractions by a factor of two immediately after its administration intravenously. The combined use of spasmolitin and gangleron is recommended for women in labor with weakness of labor at the very beginning of the period of disclosure with an established generic

activities. The use of baralgin is most indicated for a protracted course of labor due to discoordinated uterine contractions, increased basic (basal) uterine tone. It is recommended when using ^ antispasmodics and other agents that affect the function of myo- ■" measurements as an objective control to use external * tokography. The use of antispasmodics [. along with a shortening of the total duration of the birth act, ■ also leads to a decrease in the number of fetal asphyxia and! a newborn, a decrease in the frequency of operative delivery, injuries of the soft birth canal, perineal and pelvic floor muscles in women in labor with late toxicosis of pregnant women (M. V. Kutalia-Izoria, 1979).

Regulation of labor activity in parturient women with late toxicosis of pregnant women with adrenoblocking agents.

Regulation of labor activity ,

new domestic drug - pyrroxan

Neurotropic drugs, especially from the group of derivatives of the phenothiazine series, are widely used in the treatment of late toxicosis (L. S. Persianinov, 1962, M. I. Anisimova, 1962 And etc.).

Nami (V. V. Abramchenko, L. N. Kolodina, V. V. Korkhov, {■ D. I. Varfolomeev, 1975, 1976) developed a new method for the treatment and regulation of the contractile activity of the uterus in parturient women with hypertensive forms of late toxicosis. A prerequisite for the use of the drug were the features of its pharmacodynamics. Pyrroxane has a pronounced and very selective adrenoblocking peripheral and central action (S. S. Krylov, N. T. Starykh, 1973). At the same time, it is known that the adrenoblocking properties of substances are manifested primarily in the hypotensive effect. The ex- ~ Experimental studies by S. S. Krylov and N. T. Starykh showed that the mechanism of the hypotensive effect of pyrroxane, apparently, lies in the ability of the drug to block adrenoreactive systems located in the walls of blood vessels. The central adrenoblocking effect of pyrroxane is less pronounced than that of chlorpromazine. Pyrroxane does not block the anterior hypothalamus, where oxytocin is known to be produced. It intensifies the exchange of serotonin, which, as shown V studies N. S. Baksheev, Zh. T. Zubchenok, Yu. L. Rakhvalsky (1970), E. T. Mikhailenko (1978, 1980), plays an important role in the development and maintenance of the contractile activity of the uterus. Pyrroxan has a pronounced and selective adrenoblocking action (peripheral and central), especially in relation to the structures (nuclei) of the posterior hypothalamus. It should be noted here that one

Among the main advantages that are important for obstetric practice of pirroxane is that the drug is a highly effective drug for the treatment And prevention of diseases and conditions, the basis of which is an excessive increase in sympathetic tone - hypersympathicotonia, which is observed in women in labor with late toxicosis (AP Nikolaev, 1972, etc.). At the same time, pyrroxan is effective in case of mental overstrain and in the usual single dose (1-2 tablets) enhances attention and mental performance. And eliminates feelings of anxiety, tension. Taking pirroxan before going to bed promotes fast falling asleep, and awakening is easy and a state of good rest occurs. The therapeutic effect of taking pirroxan occurs within 30-40 minutes, while blood pressure normalizes, tachycardia is removed, and the state of emotional tension (feeling of fear, anxiety) is eliminated. The high therapeutic efficacy of pirroxan in these conditions is explained by the ability of pirroxan to normalize the pathological excitation of the posterior hypothalamus, which occurs in these diseases and, probably, in other pathological conditions based on hypersympathicotonia. Method of application: inside (in tablets), subcutaneously and intramuscularly.

Recommended doses: inside - 0.015 tablets (1-2 tablets 1 - 3 times a day) or 1 - 3 ml of a 1% solution 1 - 3 times a day. Seven years of experience in the use of pirroxan in medical practice did not reveal any contraindications. The drug pirroxan is approved by the Pharmacological Committee of the Ministry of Health of the Russian Federation (protocol No. 9 dated May 12, 1967) and by order of the Minister of Health of the Russian Federation No. 712 dated November 6, 1969 for use in medical practice.

S. S. Krylov, N. T. Starykh studied in detail the pharmacological characteristics of pyrroxane and showed that the effect of adrenaline on blood pressure is usually biphasic. Intravenous administration of adrenaline initially causes a short-term rise in blood pressure, followed by its decrease below the initial level. The rise in blood pressure after the administration of catechol-|mins is associated with the excitation of alpha-adrenergic receptors, and the depressor reaction is associated with the excitation of beta-adrenergic receptors. Under the influence of active a-adrenergic blocking substances, the development of the pressor effect of adrenaline instead of the pressor effect is associated with blockade of a-adrenergic receptors and with the preservation of the function of b-receptors (Ahlquist, 1948, 1962). The pressor action of norepinephrine was inhibited by the drug to a lesser degree than that of adrenaline (the effect of norepinephrine decreased by 50%, but was not reversed). That is why it is advisable to use pyrroxan V obstetric practice, because, as shown by studies conducted at our Institute, O. N. Arzhanova

(1979) with nephropathy during pregnancy, the content of renaline and norepinephrine in the blood plasma doubles and depends on the severity of toxicosis. The content of catecholamines in the urine progressively decreases. The author established a correlation between an increase in the level of norepinephrine in the blood and a form of late toxicosis. The most important side of these studies is also the position that the level of catecholamines in the blood plasma of puerperas who have undergone late toxicosis is restored slowly, reaching the norm by the 8th day of the postpartum period. The excretion of adrenaline and norepinephrine in the urine, even by the time of discharge, does not reach a normal level.

An increase in the activity of catecholaminergic systems in late pregnancy toxicosis is one of the pathogenetic links in the development of toxicosis. The use of agents that normalize the activity of the sympathetic-adrenal system, in particular, pyrroxane, should lead to a favorable clinical effect in pregnant women with hypertensive forms of late toxicosis. In experiments on isolated smooth muscle organs, pyrroxane had an adrenoblocking effect. This action extended to a- and b-adrenergic receptors embedded in the smooth muscles of various organs (uterine horn in a guinea pig, for example, etc.). However, it should still be emphasized that pyrroxane blocks predominantly a-adrenergic receptors, regardless of their location. So, in experiments on an isolated uterine horn, S. S. Krylov and N. T. Starykh in rabbits, pyrroxane at a concentration of 1.10 "6 blocked the reaction to mezaton and weakened the contractile effect of noradrenaline from 62 to 92%. Pyrroxane compared with other compounds (piperoxane , chlorpromazine, haloperidol) is the most active peripheral adrenergic blocker. It has an adrenoblocking effect in relatively low doses (0.1 mg / kg), when the neuroplegic effect is not yet manifested. Pyrroxane is also more active than haloperidol and chlorpromazine in terms of inhibition of a-adrenergic receptors of isolated organs (isolated uterine horn, etc.) by about 1.5 - 2 times.Pyrroxan, along with peripheral adrenoblocking action, has a strong and prolonged hypotensive effect with a duration of more than 4 hours.At a dose of 1 mg / kg, it reduces blood pressure by 57, 5%, dibazol at a dose of 0.5 mg / kg only by 4 - 6%, while the hypotensive effect occurred after 2 - 6 minutes. In experiments on dogs, intramuscular injection of pyrroxane caused a decrease in blood pressure by 50% from 70 mm Hg. Art. up to 35 mm Hg Art. without changes in the electrocardiogram, when taken orally at a dose of 1 mg / kg, the decrease in blood pressure occurred after 20-30 minutes and was less pronounced than with intramuscular injection. The drug also has

clear coronary dilating effect. In addition, the effect of pyrroxane on ganglionic transmission in various ganglia of the sympathetic and parasympathetic nervous systems was studied. The drug disrupts the transmission of a nerve impulse from the postganglionic endings of the sympathetic nerve to adrenoreactive structures, i.e., it has an adrenoblocking effect. The hypotensive effect is also based on the adrenoblocking effect of the drug. At the same time, pyrroxane has a weak effect on the n-cholinergic receptors of the peripheral nervous system. The sensitivity of m-cholinergic receptors does not noticeably change under the influence of pyrroxane. The drug has a weak papaverine-like effect, does not inhibit serotonin receptors. It is important that the drug has low toxicity. The pronounced effect on the central nervous system is due to the blocking effect of the substance on the adrenoreactive structures of the posterolateral hypothalamus, which is clinically indicated for its administration in states of sharp excitement, anxiety and anxiety, and also has a blocking effect on the adrenoreactive structures of the reticular formation. The drug, unlike other drugs with adrenoblocking action (chlorpromazine, haloperidol), has a milder effect on the central nervous system and has a narrower spectrum of action, i.e. it is

| lyatsya more pure adrenoblocker.

S. S. Krylov developed experimental prerequisites

(Ci of the therapeutic efficacy of the drug in experiments on monkeys (hamadryas baboons) in the elimination of hypertensive conditions. Intramuscular administration of pyrroxane at a dose of 0.5 mg / kg led to a decrease in maximum blood pressure by 29% and minimum blood pressure by 29% and minimum blood pressure by 45% When the dose was increased to 0.75-1.0 mg / kg, the drop in blood pressure occurred in the first 6-15 minutes and after about 1 hour it reached its maximum and in the next 2 hours it remained at a low level: the maximum was on average 27% and a minimum of 46%.Recovery of blood pressure was slow within 3-4 days.Thus, pyrroxane is effective in conditions associated with pathological excitation of the tone of the sympathetic nervous system.

Under our supervision there were 169 women aged 18 to 45 years. 157 (92.8%) of them had a pure form of late toxicosis and 12 (7.2%) had a combined form (toxicosis developed

| : against the background of hypertension stage I-II). By degree

"The severity of toxicosis, the patients were distributed as follows: hypertension in pregnant women was in 25 (4.8%) women, nephropathy of I degree in 86 (51%), II degree in 32 (18.9%), III degree in 21 ( 12.3%) and preeclampsia in 5 (3.0%).

: ki) 129 women and administered orally 15 mg 2 to 3 times a day in 40 women (Group 2). During childbirth, pyrroxan

used only parenterally. The study of the dynamics of blood pressure (measured before and after 30 - 60 minutes after the administration of the drug, after 2 - 4 hours) showed that in group I, systolic blood pressure was under; the influence of the drug in 119 (92.5%) ± 8.1% (women decreased by 10 -30 mm Hg, and diastolic blood pressure in 112 (86.9 ± 11.2%) by 5 - 20 mm Hg. In the 2nd group, a decrease in systolic blood pressure by 5–20 mm Hg was observed in 33 (82.5 ± 6.0%) women in labor and diastolic in 39 (97.5 ± 6.0%). the rest of the women, the hypotensive effect was absent, despite the repeated administration of the drug.A sedative effect occurred relatively quickly - after 2-4 hours, depending on the method of administration of the drug, especially noticeable in emotionally unstable women.In puerperas, before taking the drug, suffering from insomnia, sleep improved (L. N. Kolodina, V. V. Abramchenko, : L. N. Granat, 1975). Of particular interest is the study of the effect of pyrroxane on lactation. In parturients who have undergone late toxicosis of pregnant women, lactation disorders are often noted. According to V. P Miroshnichenko (1957), insufficient lactation occurs in 74% of puerperas who suffered from late toxicosis of pregnant women, according to L. N. Granat, 3. V. Svetlova, T. A. Kucherenko (1967) in 20.4%. We have studied the effect of pyrroxane on lactation in 93 mothers. The daily amount of milk was taken into account and its biochemical study was carried out in dynamics with the determination of total and whey protein according to the Kjeldahl micromethod, lactose according to Bertrand and fat in Gerber butyrometers. In 83 (89.3%) puerperas treated with pirroxane, lactation was normal, 1 (1.1%) increased and 9 (9.6%) decreased. Data on the chemical composition of milk in puerperas treated with pyrroxane showed that under the influence of pyrroxane there was no significant change in the qualitative composition of milk compared with the control group. However, the content of lactose in milk in women treated with pyrroxane is slightly higher than in the control group. Analysis of lactation function indicates the absence of a negative effect of the drug on lactation in patients with late toxicosis. The mechanism of the effect of the drug on lactopoiesis requires further study.

Regulation of labor by pyrroxane

One of the urgent problems of modern obstetrics is the regulation of labor activity in parturient women with various forms of late toxicosis (L. S. Persianinov, 1971, V. S. Smirnova, L. E. Manevich, I. Y. Levashova, 1974, L. P. Sukhanova, 1976; Insler, Homburg, (1979) and others).

At the same time, one of the important prerequisites for prescribing drugs to regulate the contractile activity of the uterus in this contingent of women in labor is the increased activity of the sympathetic nervous system (hyperspathy) - which

(A.P. Nikolaev, 1972, Jenny, 1963, Hauser, Mamboufq, 1973) and the prevalence of vascular disorders in the clinical picture of V.N. Gorovenko, 1975, etc.). As is known, the mediator of sympathetic nerves that abundantly innervates the uterus - nora-renaline has a depressing effect on the contractile activity of the uterus (Wurtman, Chu, Axelrod, 1963), and adrenaline, produced by the adrenal medulla, causes relaxation of the myometrium in the last trimester of pregnancy (S. V . Anichkov, 1974). From this it is clear that the blockade of adrenoreceptors of the uterus, caused by the use of adrenoreceptor blocking drugs, in particular, pyrroxane, can prevent the inhibitory effect of the mediator of norepinephrine and hormonal adrenaline on the motility of the woman's uterus during childbirth. O. N. Arzhanova (1979) conducted on the basis of the obstetric clinic showed that the content of norepinephrine in the blood plasma during childbirth with the edematous form of late toxicosis is 1.3 times lower, and with nephropathy two times lower than during normal childbirth. The data obtained indicate a decrease in the functionality of catechol-minergic systems during childbirth with late toxicosis. An increase in the number of complications in childbirth observed in women with toxicosis correlates with the degree of decrease in the activity of the sympathetic-adrenal system. Based on these data, in the management of childbirth in women in labor with hypertensive forms of late toxicosis, it is necessary to use such agents that would not only ensure the normalization of blood pressure, but also have a beneficial effect on the motor function of the uterus. In order to regulate labor activity, we used pyrroxane in 82 women in labor with hypertensive forms of late toxicosis (V. V. Abramchenko, L. N. Kolodina, V. V. Korkhov, D. I. Varfolomeev, 1976). There were 60 primiparas, 22 multiparous. The average age of women in labor was 27 ± 0.7 years. According to the severity of toxicosis, the parturient women were distributed as follows: nephropathy of the 1st degree in 55 (67%), nephropathy of the 2nd - 3rd degree in 27 (33%). The pure form of toxicosis according to the classification of S. M. Becker was in 61 (74.5%) and the combined form in 21 (25.5%). at the NII AG them. D. O. Otta RAMS (V. V. Abramchenko, D. I. Varfolomeev, 1976). Internal hysterography was carried out according to the principle of direct measurement of intrauterine pressure using an open polyethylene catheter inserted into the amniotic sac through the cervical canal. Research was carried out in dynamics throughout the entire period of disclosure and the period of exile. In total, mathematical processing under-

more than 5000 uterine contractions were delivered, the analysis of the obtained data was carried out according to 16 parameters for every 10 minutes.

Method of administration of pyrroxane. With the opening of the accessory pharynx by 3 - 4 cm And establishing regular labor activity, pyrroxane was first administered at a dose of 15 mg (1.5% - 1 ml), intramuscularly in order to determine the sensitivity of the woman in labor to the drug. If at the same time blood pressure did not decrease, then the dose increased to 30 mg (1.5% - 2 ml), intramuscularly. Subsequent administration of the drug is permissible only after 1.5 - 2 hours. We did not observe orthostatic collapse when using pyrroxan. There are no contraindications to the use of the drug during childbirth. The hypotensive effect was noted in 75 (91.5%) parturient women. The duration of labor in primiparas with pyrroxane was 13.1 ± 0.3 hours, in multiparous - 8.1 ± 0.4 hours. ., and in multiparous - 9 hours 38 minutes ± 26 minutes. (R< 0,001). Таким образом, отмечено стастически значимое укорочение длительности родов у первородящих.

At the same time, before the introduction of pyrroxan, the average duration of labor was 6.8 ± 0.85 hours, in primiparas And 4.5 ± 0.69 hours in multiparous, then after the introduction of pyrroxan, respectively, 5.2 ± 0.3 hours and 3.9 ± 0.48 hours. women versus 40% in control studies. There was no negative effect of pyrroxane in the dosages used by us on the state of the fetus and newborn. The average Apgar score was 8.7 ± 0.47 points. Neonatal asphyxia was in 2 children (2.4%), in control studies (1755 children) in 2.5% with late toxicosis. One child died due to pneumonia. The average amount of blood loss in the postpartum And in the early postpartum period was 155.7 ± 17.6 ml versus 251 ± 18 ml in the control. Blood loss over 500 ml was observed in 4 (4.9%) versus 12.6% in controls (P = 0.05). Delivery operations were used in 7.4% of parturient women using pyrroxane versus 12% in control studies.

The study of the contractile activity of the uterus in parturient women according to internal hysterography in 35 primiparas And 5 multiparous showed that after the introduction of pyrroxane there is a statistically significant difference, when processing data with the determination of confidence intervals according to R. B. Strelkov (1966), in a number of indicators of the motor function of the uterus. So, the total intrauterine pressure of contractions, the tone of the uterus, the intensity of “pure” contractions clearly increase, the duration of the intervals between contractions decreases,

increase in intrauterine pressure during contractions, "" more precisely systole And diastole, pulse pressure rises. In women in labor, in the presence of painful contractions, suffering from late toxicosis, we (L. N. Kolodina, V. V. Abramchenko, D. I. Varfolomeev, 1976) developed a method for the combined use of an a-blocker - pyrroxane with promedol. A similar combination was used in 69 women in labor. First, pyrroxane is introduced according to the method described above. And after 30-60 minutes, 20-40 mg of promedol is administered. In case of insufficient effect, repeated administration of the drugs is permissible after 2-3 hours. In 58 women in labor (85%), a pronounced hypotensive and analgesic effect was noted. There was no adverse effect of this combination of substances on the body of the woman in labor, the contractile activity of the uterus and the condition of the fetus And newborn. When using pyrroxane, as well as its combination with a solution of promedol according to the above method, a decrease in the frequency of operative delivery in parturient women with hypertensive forms of late toxicosis was revealed (V. V. Abramchenko, L. N. Kolodina, N. I. Dontsov, 1976) . The positive effect of pyrroxane in terms of the regulation of labor activity, as well as its enhancement, is probably due to the fact that, on the one hand, the pharmacological blockade of uterine adrenoreceptors not only suppresses the relaxing effect of catecholamines on the uterus, but also simultaneously enhances the stimulating effect of serotonin on contractile activity of the myometrium, as shown in the studies of I. V. Duda, I. M. Starovoitov, A. I. Balakleevsky, D. I. Budrevich (1973). It is possible that under the influence of pyrroxane, such an optimal ratio of the amounts of monoamines (adrenaline, noradrenaline and serotonin) is created in the blood and in the tissue of the uterus, which contributes to the normalization of labor activity (N. S. Baksheev, 1973). Obviously, in the mechanism of the normalizing action of pyrroxane, which is not only a peripheral, but also a central adrenergic blocker (S. S. Krylov, N. T. Starykh, 1973), the contractile activity of the myometrium during childbirth has a certain inhibitory effect of the drug on the central adrenergic systems, in particular, and on the so-called sympathetic centers, localized in the posterior hypothalamic region.

The use of pyrroxan for the treatment of residual effects of the hypertensive form of late toxicosis in puerperia

One of the program issues at the IV Congress of Obstetricians and Gynecologists of the RSFSR (1977) was the question of the rehabilitation of women after obstetric pathology. According to Yu. I. Novikov (1977), neurological symptoms and hypertension were detected even 2–3 years after severe toxicosis of pregnant women.

With late toxicosis, many indicators in a woman's body do not reach a normal level by 8-10 days (V. I. Grishchenko, 1968, 1977, O. N. Arzhanova, 1979). Our data show (V. V. Abramchenko, 1973) that even with the use of highly effective anticholinergic and adrenoblocking and analgesic drugs in childbirth, 30% of puerperas still have elevated blood pressure, especially with combined forms of late toxicosis. Here it is necessary to point out that the choice of formicological agents for the rehabilitation of puerperas who have undergone late toxicosis should be carried out not only taking into account the characteristics of the toxicosis itself, but also the characteristics of the lactation function in such women. In this regard, pyrroxane proved to be effective. In the process of monitoring 130 puerperas treated with pyrroxane (L. N. Kolodina, V. V. Abramchenko, 1977), the sedative effect of the drug, which was especially pronounced in emotionally unstable women, attracted attention first of all. The hypotensive effect was noted in 90% of puerperas. The results of the analysis of lactation function indicate a favorable effect of pirroxane on lactation in patients with late toxicosis. Thus, hypogalactia was observed in 8.5% of puerperas treated with pyrroxane versus 19.2% in control. A biochemical study found that the colostrum of women treated with pyrroxin was significantly higher in protein compared to the protein content in the colostrum of women in the control group. In the mature milk of such puerperas, there is more milk sugar. The mechanism of the favorable effect of pyrroxane on lactation needs to be studied.

It is quite possible that a drug that blocks adrenoreactive systems prevents the damaging effect of an excess amount of norepinephrine on adrenoreactive systems and associated processes in the mammary gland.

Violation of the function of the sympathetic-adrenal system is characteristic of patients with late toxicosis (L. V. Timoshenko, . 1968, O. N. Arzhanova, 1979, etc.). By analogy with other tranquilizers, the effect of pyrroxane on the hypothalamic centers, which are in charge of the secretion of the prolactin-inhibiting factor, cannot be excluded. Clinical observations on the lactopoetic effect of pirroxane are consistent with experimental data on the inhibitory effect of pirroxane on FSH activity in the pituitary gland, which suggests the possibility of a disinhibitory effect of the drug on prolactin secretion (V. V. Korkhov). In the postpartum period, pyrroxan can be used either intramuscularly at 1-2 ml of a 1.5% or 1% solution 2-3 times a day or orally at 30 mg 2-3 times a day. The course of treatment is 5 - 8 days.

Contraindication for treatment with pirroxan is arterial hypotension of any etiology. For the purpose of prevention

possible orthostatic collapse of the puerperal within two hours after the introduction of an intramuscular preparation | should be on bed rest.

Regulation of labor activity

betamimetic drugs

(partusisten, yutopar, ritodrin, brikanil)

IN In the literature, there are isolated reports of the combined use of blocking beta-adrenergic drugs to induce and stimulate labor. So, in the work of Urban (1973, 1977), propranolol (Inderal) was used for this purpose. The author used the drug when the uterus did not respond to the Smith oxytocin test. Inderal was administered at a dose of 1-3 mg, and after the introduction of 1 mg of the drug, it was noted that the uterus began to contract more strongly. If subsequently oxytocin was administered at 8-12 drops per minute (5 units per 500 ml of saline) together with inderal at a dose of 1-2 mg, then normal labor activity developed. At the same time, the use of Inderal in normal labor; activity leads to its discoordination.

> In order to regulate labor activity in parturient women with late toxicosis in the presence of discoordinated and excessive labor activity, we used partusisten in 40 parturients (10 of them multiparous) by intravenous drip infusion. The rationale for the use of beta-mimetics in childbirth was the following circumstances. We (V. V. Abramchenko, 1973), when studying the activity of the histamine-histaminase system according to the method of G. N. Kassil and I. L. Vaisfeld, found that in women in labor with late toxicosis of pregnant women, especially in the presence of pronounced psychomotor agitation during childbirth during in the presence of painful contractions, the amount of histamine increases by 2 times or more compared to the data in the normal course of the birth act. With the use of neurotropic agents, a 2.5-fold decrease in the concentration of histamine in the blood was noted. The activity of histaminase, both before and after the administration of the drug, does not change. A clear correlation was found between the content of histamine and the nature of labor activity according to the data of three-channel external hysterography: with an increased amount of histamine, violent labor activity is noted. Therefore, the use of adrenergic substances is a favorable factor in terms of the normalization of labor activity in this contingent of women in labor. R. F. Sakharova (1969) also showed that rapid childbirth occurs against a background of higher histamine concentrations both in the mother's body and in the fetus. In connection with the use of adrenergic substances to regulate labor activity, we studied the activity of the sympathetic-adrenal system in women in labor with late toxicosis.

Electrophysiological studies have established that changes in the functional state of the cortex under the influence of adrenaline are due not to its direct effect on the cortex, but to an increase in the tonic effects of ascending activating systems. So, in studies, N. N. Traugott et al. (1968) it was shown that during the period of action of chlorpromazine, the hypothalamic-pituitary system becomes inaccessible to the stimulating action of adrenaline, to which this system is usually highly sensitive. We also did not reveal changes in the content of adrenaline, norepinephrine, dopamine and dopa after the administration of chlorpromazine (determination of these biogenic amines was carried out according to the method of E. Sh. Matlina et al.). According to our data from 11 women in labor, when determining the concentration of adrenaline before and after the administration of adrenolytic agents (chlorpromazine), the average concentration of adrenaline was 2.77 ± 0.44 μg / day with fluctuations from 0.2 to 7.9 μg (per day) . Excretion of norepinephrine was 8.23 ​​± 1.86 μg/day with fluctuations from 1.0 to 39.3 μg/day. Dopamine excretion was 0.92 ± 0.1 (from 0 to 4.8 µg per day). Dopa excretion was 4.5 ± 0.23 μg per day with fluctuations from 0 to 12.5 μg. (V. V. Abramchenko, 1973, M. A. Petrov-Maslakov, V. V. Abramchenko, 1977). It is very likely, using the example of the administration of chlorpromazine, that the administration of adrenergic substances in parturient women with late gestational toxicosis makes it possible to preserve the functional and reserve capabilities of the sympathetic-adrenal system during the birth act. Thus, the introduction of drugs with adrenergic action, apparently, causes, in addition to reducing the activity of the reticular formation, at the same time provides a functional blockade of the hypothalamic-pituitary system. These data are also confirmed by a clinical study of the state of the cardiovascular system. ■

Method of introduction of partusisten. To prepare an intravenous infusion, it is recommended to dilute 1 ampoule (10 ml) of partusisten in 250 ml of sterile saline or 5% glucose solution. It must be remembered that 20 drops corresponds to 1 ml = 2 µg of partusisten, i.e. 10 drops of partusisten contain 1 µg of the drug. At the same time, it is necessary to regularly monitor blood pressure and pulse rate, as well as the fetal heartbeat, during the infusion of partusisten. In normal labor activity, the introduction of partusisten with a frequency of 8-16 drops per minute led to a decrease in labor activity and a decrease in the basal tone of the uterus by 5-7 mm Hg. Art. At the same time, according to the data of two-channel internal hysterography and cardiotocograph by Hewlett-Pakaard and Siemens, we revealed, first of all, regardless of the dose, a decrease in the amplitude of uterine contractions (intensity of contractions), then the frequency and duration

uterine contractions and the basal tone of the uterus, while the effect of the drug on various parts of the uterus (bottom, body, lower segment of the uterus), depending on the nature of labor, the type of anomaly of labor, is significantly different. With an increase in the frequency of drops over or within 24 per minute, it leads to a complete cessation of labor. There was no adverse effect of partusisten on fetal heart rate and motor activity. In a number of fetuses, in the presence of deviations in the cardiotocogram due to abnormalities of labor activity, along with the normalization of contractions, there was also a normalization of the indicators of the cardiac and motor activity of the fetus, probably due to an improvement in the uteroplacental and umbilical-placental blood circulation. An identical pattern was also revealed when determining the state of the fetus according to the oxygen test. After the infusion of the drug, labor is normalized, while the activity of the lower segment remains quite high.

Identical regularities were also obtained by us when 20 primiparas were treated with yutopar (ritodrin) from the Dutch company Philips-Duphar. The drug was also used intravenously, in 250 ml of sterile saline. At the same time, the administration of the drug began with an initial dose of 0.05 mg / min and gradually every 10 minutes the dose of the drug increased by 0.05 mg / min until normalization of labor activity was noted, both according to clinical observation and a permanent record. intrauterine pressure or cardiotocography. Our observations show that the clinically effective dose of ritodrine in the treatment of discoordinated and excessive labor activity in parturient women with late toxicosis is in the range of 0.2 - 0.35 mg / min. The antispasmodic effect of utopar on uterine contractions was also revealed, while the duration of labor, taking into account the degree of opening of the uterine os, by the beginning of the introduction of utopar showed that, on average, a shortening of the duration of labor by 2 hours and 15 minutes was noted. There was no adverse effect of Utopar on the condition of the fetus and newborn. In the future, until discharge from the hospital, the development of children without features. In methodological terms, it is extremely important to emphasize that the use of betamimetics, according to the method used by us, must be carried out in the position of the woman in labor on her side, at least 15 °, to prevent possible hypotensive reactions. The advantage of utopar over partu-systen, even with prolonged use up to 4-6 hours, is a smaller number of side effects. The third drug that we have tested for the treatment of labor anomalies is brikanil, produced by the Egit pharmaceutical plant, Hungary under license from the Swedish

which firm Astra. Bricanil (terbutaline) has been used in clinical practice since 1970, especially widely in the treatment of bronchial asthma and other pathological conditions. As is known, the smooth muscles of the bronchi and uterus contain beta 2 type receptors. Their stimulation leads to relaxation of both organs. Under in vitro conditions, bricanil blocks the contractility of the isolated human uterus and the drug has therefore found the widest application for the treatment of threatened preterm birth. It should be noted that beta-mimetics such as bricanil can have a beneficial effect on the patency of the bronchial tree in parturient women with late toxicosis of pregnant women. So, in studies conducted at our Institute by A. Kh. Iseev (1980), it was shown that by the end of normal pregnancy, pulmonary and alveolar ventilation is significantly increased by more than 1.5 times compared with the corresponding values ​​in non-pregnant women. At the end of a normal pregnancy, both at rest and after exercise, no significant changes in bronchial patency were found. However, a tendency to a slight decrease in bronchial patency was revealed, which is expressed in a change in the ratio between the maximum inspiratory and expiratory volumetric velocities. This, apparently, is associated with a change in the structure of the vital capacity of the lungs: a decrease in the expiratory reserve volume as a result of an increase in intra-abdominal pressure and a high standing of the dome of the diaphragm in pregnant women, a weakening of the activity of the abdominal muscles involved in exhalation, an increase in the content of biologically in the blood by the end of pregnancy. active substances of bronchoconstrictive action - histamine, serotonin, acetylcholine, prostaglandin F 2 a, etc. With moderate toxicosis, according to A. Kh. to a greater extent prevails over the duration of inspiration than in healthy pregnant women. This may acquire clinical significance when pregnancy is combined with pulmonary pathology or under the influence of endo- or exogenous substances that can change bronchial patency.

There are isolated reports of the use of bricanil in urgent delivery (Andersson et al., 1975). At the same time, with the infusion of bricanil at a rate of 5–20 μg/min, it effectively reduced the activity of the uterus caused by prostaglandin F21. The effect appeared immediately. Only a weak tachycardia was noted in parturient women; the authors did not reveal other side effects.

We used brikanil in the form of intramuscular injections of 1 ml (0.5 mg) of terbutaline sulfate in 1 ml of an aqueous solution. One tablet contains 2.5 mg of terbutaline.

No side effects were detected in 15 parturient women with intramuscular administration of bricanil.

Concomitant use of beta mimetics with prostaglandins

We (V. V. Abramchenko, N. I. Dontsov, 1979) developed a method for regulating labor activity in parturient women with late toxicosis of pregnant women with a combination of beta-mimetics and prosta-I glandin. The rationale for the combined use of prostaglandins and betamimetics was the following circumstances. Pharmacological studies of A. N. Kudrin, G. S. Koroz (1977) showed that blocking the inhibitory beta-adrenergic receptors of the rabbit myometrium does not affect the excitation of its a-adrenergic receptors. In addition, the authors found that prostaglandin stimulation F 2a specific functional structures of plasma membranes of myometrial cells create favorable conditions for the manifestation of excitatory activity of a-adrenergic receptors. Secondly, modern research has established that the peripheral part of the sympathetic nervous system is formed by neurons whose bodies are concentrated in the so-called segmental ganglia I. Axons of ganglion nerve cells innervate the heart, smooth muscles of blood vessels, and internal organs | and intramural ganglia; these axons form "long" G postganglionic sympathetic nerves. In addition, there are |, "short" postganglionic sympathetic nerve fibers that originate from cells that form ganglia of non-| indirectly in the organs of the small pelvis - the uterus, etc. (O. M. Avakyan, 1977, etc.). We used prostaglandin in 60 women at full-term pregnancy fta.(enzaprost) and prosta-I glandin E 2 inside. In 22 parturient women with late toxicosis, with -I, the beta-mimetic with prostaglandin changed, in particular, partu-sisten and yutopar, respectively, at doses of 0.05 mg / min and 1.5 - 3 μg / min.

Method of application of drugs: in women in labor with I weakness of labor activity, especially with elements of disco-1 coordinated labor activity, 5 mg of prostaglandin was dissolved in 500 ml of saline and administered at a frequency of drops of 8-12 per minute, if there was no effect, the frequency of drops was increased every half an hour at 4, maximum 10 to 40 drops per minute. The maximum dose of enzaprost during labor was 10 mg (2 ampoules). Beta-adrenergic agonists began to be administered 30-45 minutes after prostaglandin induction, if contractions appeared on the hysterograms, which were of a discoordinated nature, or the basal tone of the uterus increased, with an increase in the frequency of contractions more than 4-5 in 10 minutes, it is advisable to administer beta-mimetics with frequency of drops 6-10 per minute. The use of beta

mimetics should be carried out under the control of external or internal hysterography. Use of a combination of beta mimetics And prostaglandin (enzaprosta) in parturient women with late gestational toxicosis shows that the total duration of labor in nulliparous women was 16 hours 08 minutes. ± ± 0 h. 54 min., in multiparous - 13 h. 06 min. ± 42 min.

The results of the studies show that the combination of the use of prostaglandin and beta-mimetic increases And lengthening of uterine contractions and a moderate increase in basal tone. However, one of the main actions of this combination is a pronounced effect in the form of increased activity of the lower segment of the uterus. Apparently, the mechanism of action of prostaglandins in combination with beta-adrenergic mimetics is not only to increase the contractility of the myometrium, increase muscle tone and increase the amplitude of uterine contractions, the coordinated nature of uterine contractions, but also in the selective effect of these substances on the lower segment of the uterus.

In conclusion, it must be emphasized that the main indications for the use of beta-agonists in childbirth are:

1) childbirth, in which there is an excessively intense force of uterine contractions - 80-100 mm Hg. Art.; 2) in the presence of excessive uterine contractions - 5 or more uterine contractions in 10 minutes; 3) with a combination of excessive intensity and frequency of uterine contractions; 4) with increased numbers of basal tone (over 12 mm Hg); 5) discoordinated uterine activity with the presence of contractions of an irregular shape, a violation of their rhythm, the rhythm of double and triple contractions; 6) in case of violation in the state of the fetus due to anomalies of labor activity, i.e. resuscitation of the intrauterine fetus with beta-mimetics both during the period of disclosure and during the period of exile.

The reasons for the onset of labor activity have not yet been established.

Theories of the causes of the development of labor activity. To explain the causes of the onset of labor, many theories have been put forward, many of which are of historical interest.

According to Hippocrates, childbirth occurs because the fetus, due to hunger that occurs at the end of pregnancy, itself leaves the uterine cavity, resting its legs against its bottom (head first). According to the "foreign body" theory, childbirth occurs because the intimate connection between the uterus and the fetus is disrupted due to fatty degeneration of the tissues of the placenta and endometrium.

Subsequently, various theories of the onset of labor were put forward (mechanical, immune, placental, chemical, hormonal, endocrine).

Supporters of the mechanical theory believed that the causes of childbirth are the excitation of nerve receptors located in the lower segment of the uterus, as a result of pressure from the fetal head.

With the development of the doctrine of immunity, the emergence of the immune theory is associated, according to which, in response to the release of syncytiotoxins in

"Currently, in addition to spontaneous childbirth, there are: a) induced labor - artificial labor induction according to indications from either the mother or the fetus; b) programmed childbirth involves the process of giving birth to a child in the daytime, convenient for the doctor. For this purpose, labor induction is carried out at the time of the expected birth with the full maturity of the fetus.

The placenta produces antibodies called syncytiolysins. By the end of pregnancy, the amount of syncytiotoxins increases so much that they are not neutralized. Due to this, the uterus becomes excitable, the impulses necessary for contraction arise in it. However, the search for specific syncytiotoxins has not been successful. Another mechanism of influence of immunological reactions on the development of labor activity is possible. According to some scientists, the birth of a fetus can be likened to a transplant rejection reaction.

According to the placental theory, childbirth begins with the occurrence of various changes in the placenta, which consist in the degeneration of the villi and the cessation of the inhibitory effect of the trophoblast on the contractile activity of the uterus, as well as with the appearance in the placenta of substances that cause contractions and the onset of labor. This theory has not been confirmed.

According to the chemical theory, the onset of childbirth is associated with a change in the composition of inorganic substances in the uterus and the ionic environment in the body of a pregnant woman, with the accumulation of carbonic acid and other substances that cause muscle contraction.

With the development of endocrinology, the causes of the onset of childbirth began to be explained by a change in the hormonal background before childbirth, contributing to an increase in the contractility of the uterus (endocrine theory).

The presented list of theories of the onset of labor indicates the complexity of the changes that occur in pregnant women before and during childbirth.

Modern ideas about the causes of childbirth. Childbirth proceeds in the presence of a formed "birth dominant", which is a single dynamic system that combines both higher centers of regulation (central and autonomic nervous system, hormonal regulation) and executive organs (uterus and fetoplacental complex) (Fig. 5.1).

A normal birth act is determined by the involvement of the cerebral cortex in the dominant process, in particular the temporal lobes of the cerebral hemispheres, as well as a significant increase in interhemispheric connections that facilitate the coordination of somatic functions.

An important part of the coordination centers of labor activity is located in the subcortical structures of the brain: in the hypothalamus - in the amygdala nuclei of the limbic complex, the pituitary gland.

Before the onset of childbirth, inhibitory processes in the cerebral cortex gradually increase and the excitability of the subcortical structures that regulate labor activity increases. At the same time, the excitability of the peripheral parts of the nervous system increases, in particular interoreceptors that transmit excitation from the genital organs. Afferent impulsation from the uterus, which forms unconditioned reflexes associated with the birth act, is enhanced due to the maturity of the fetoplacental complex. Before childbirth, it exceeds the threshold of sensitivity of perceiving subcortical structures, contributing to the onset of childbirth.

The severity of the reflex reactions underlying childbirth depends on the tone of the various parts of the autonomic nervous system that innervate the uterus. All parts of the uterus (body, lower segment) have a double

Rice. 5.1. Regulation of the contractile activity of the uterus (scheme). Solid arrows - activation (stimulation), dotted arrows - inhibition (suppression): a - a-adrenergic receptors; p - p-adrenergic receptors; \X - M-cholinergic receptors.

autonomic innervation. Adrenergic innervation predominates in the longitudinally located muscle bundles in the body of the uterus. Cholinergic innervation is observed mainly in circular and spirally located muscle fibers, located mainly in the lower segment of the uterus. M-cholinergic receptors are also located there. Adrenoreceptors in the uterus are represented by two types: ap and a2-adrenergic receptors. They are located on the membrane of smooth muscle cells. ospAdrenoreceptors cause an increase in excitability, tone and contractile activity of the myometrium; p 2 ~^P eHO P eL l enTO P bI have the opposite effect on the myometrium. Impact on P2-adrenergic receptors causes a decrease in tone, excitability and contractile activity of the uterus. Before childbirth, the number and activity of oq-adrenergic receptors and M-cholinergic receptors increase.

Vegetative regulation of uterine contractions is carried out through mediators, the main of which are acetylcholine, adrenaline and norepinephrine.

Acetylcholine has a stimulating effect on the muscles of the uterus.

Before childbirth and during childbirth, a high level of the active form of acetylcholine is observed in the blood plasma of pregnant women, while at the same time a low activity of acetylcholinesterase is observed.

Catecholamines (epinephrine, norepinephrine) mediate adrenergic

cal influence on the myometrium, interacting with smooth muscle cells. The activating effect of catecholamines is mainly realized by their action on adrenergic receptors of smooth muscle cells of the myometrium. The inhibitory effect of catecholamines on the myometrium is associated with their interaction with β-adrenergic receptors of smooth muscle cells.

Features of the nervous regulation of labor activity are associated with a change in the hormonal status before childbirth. Only in the presence of certain hormonal ratios are possible reflex excitability of the uterus and those neurophysiological changes in which it is able to contract regularly throughout childbirth. Of the whole complex of regulatory components that duplicate each other in the period of preparation for childbirth, an increase in the synthesis of estrogens (mainly their active fraction - estradiol) is of particular importance against the background of a decrease in the level of the main pregnancy hormone - progesterone, which blocks the contraction of the muscles of the uterus. Before delivery, the content of progesterone and its metabolites in the blood and urine decreases, and the ratio of estriol / pregnandiol in the urine is 1:1 (during pregnancy 1:100).

Under the influence of estrogens, the following changes occur:

The blood flow to the myometrium increases, the intensity of redox processes, the synthesis of myocardial contractile proteins
metria (actomyosin), energy compounds (ATP, glycogen) and
uterotonic prostaglandins;

The permeability of cell membranes for ions increases (K +, Ca,
Na), leading to a decrease in the resting membrane potential, an increase in the sensitivity of myometrial cells to irritation;

Calcium is deposited in the sarcoplasmic reticulum;

The activity of phospholipases and the rate of "arachidonic cas" increase.
kada" with the formation of prostaglandins.

Such changes contribute to the intensification of the contractility of the uterus, the acceleration of the "maturation" of its neck.

In the development of labor, in addition to estrogens, prostaglandins play a key role, which, according to modern concepts, are the main stimulants for the onset of labor. The place of synthesis of prostaglandins in the pregnant uterus is the fetal (amnion and chorion) and decidua. At the same time, prostaglandin E (PGE) is formed in the amnion and chorion, and both PGE and nrF 2 a (maternal) are synthesized in the decidua and myometrium. The production of prostaglandins at the end of pregnancy is due to the processes of aging and degeneration of the structural elements of the placenta, decidua, amnion, since these processes are associated with the activation of phospholipases and the formation of arachidonic acid, and subsequently - prostaglandins. Prostaglandins stimulate the following processes:

Formation on the membrane of cc-adrenergic receptors and receptors for other
uterotonic compounds (acetylcholine, oxytocin, serotonin);

Ensuring automatic contraction of the uterus (contractions);

Inhibition of oxytocinase production.

Along with an increase in the synthesis of estrogens and prostaglandins, an increase in the activity of other neurohumoral mediators and hormones (oxytocin, serotonin, kinin, histamine) is important for the onset of labor.

Oxytocin is an important regulator of uterine contractility. It is considered by many authors as a triggering factor in the development of labor activity. Oxytocin is a synergist of acetylcholine and prostaglandins. Its plasma concentration increases with increasing gestational age. The effect of oxytocin on the contractile activity of the uterus depends on the hormonal background, primarily on the optimal level of estrogen, as well as the functional state of the uterus, its readiness for spontaneous activity.

The action of oxytocin is associated with the following processes:

Strengthening the membrane potential and increasing the excitability of the muscle cell;

An increase in the rate of binding of acetylcholine by myometrial receptors and its release from the bound state;

Excitation of ai-adrenergic receptors;

Inhibition of cholinesterase activity.

As a result of the action of oxytocin, the tone of the uterus increases, the frequency and amplitude of contractions are stimulated.

Serotonin has a pronounced effect on the state and function of myometrial cells, inhibits the activity of cholinesterase and enhances the action of acetylcholine, promotes the transfer of excitation from the motor nerve to the muscle fiber.

The action of serotonin on the uterus can be carried out in two ways: directly on the myometrium through a-receptors and through the central nervous system by increasing the production of oxytocin by the neurohypophysis.

Kinins increase the contractility of the uterus by increasing the rate of blood flow in it.

Histamine, which promotes the production of oxytotic substances by the pituitary gland, has a certain importance in the development of labor activity.

There is an assumption that changes in hormonal relationships in the mother before childbirth are closely related to the degree of maturity of hormonal regulation in the fetus, which is genetically determined by the completeness of the processes of its growth and development. First of all, the maturity of the epiphysis-hypothalamic-pituitary system of the fetus is important.

The effect of fetal hormones on the preparation and onset of labor consists of the following points:

With an increase in the level of fetal corticotropin in the mother's blood
the content of estradiol increases and the amount of progesterone, choriogonadotropin and choriomammotropin (placental lactogen) decreases;

The oxytocin released before birth in the fetus acts similarly
but maternal oxytocin;

Before childbirth, the level of melatonin in the blood of the fetus rises, and in
mother - goes down. These changes in the concentration of melatonin contribute to the restructuring of steroid hemostasis and the formation

niyu estrogen background in the body of a pregnant woman. Melatonin changes the ratio of prolactin / foli / lutropin in the direction of increasing the last two. As a result, there is an increase in the synthesis of estriola. Along with this, a decrease in the level of melatonin in the mother's blood leads to the release of leukotrienes (slowly reacting substances of anaphylaxis), which in turn leads to the activation of keylon activity and inhibition of a further increase in the weight of the fetus, its organs and tissues and contributes to the activation of the mechanisms of preparing the body of a pregnant woman for childbirth. Simultaneous suppression of the synthesis of immunosuppressants prolactin and hCG leads to an increase in transplantation immunity and stimulates the rejection of the fetus as an allograft;

Ischemia of the membranes of the fetal egg before childbirth, due to
increase in intrauterine pressure, activates "arachidonic
cascade" with the release of uterotonic prostaglandins.

Along with changes in the nervous and humoral regulation before childbirth, significant changes occur in the reproductive system, including the uterus.

The contraction of the muscles of the uterus, as well as other organs (heart, blood vessels), is based on the process of converting chemical energy into mechanical energy.

Of particular importance for the onset of labor are the following processes occurring in the uterus:

An increase in the intensity of metabolic processes in the myometrium,
oxygen consumption rate (3.5 times), reduce the content
body protein actomyosin (by 25%), glycogen, glutathione, phosphorus compounds (ATP, creatine phosphate, phosphocreatinine), which play an important role in the energy processes of muscle tissue;

Changes in the ratio between muscle and connective tissue in
the direction of the sharp predominance of the first of them, especially in the body of the uterus.

As a result of changes occurring in muscle cells, the membrane potential decreases, their excitability increases, spontaneous activity increases, sensitivity to contractile substances increases.

With the onset of childbirth, a group of cells is formed in the uterus, in which excitation initially occurs, subsequently spreading to the entire uterus. This area is called the pacemaker ("pacemaker"). It is located in the bottom of the uterus, closer to the right corner.

Changes in the ratio of hormones and biologically active substances that affect the excitability and contractile activity of the uterus before childbirth take place in several stages: the first stage is characterized by the state of maturity of the hormonal regulation of the fetus; the second stage - activation of estrogens and changes in the uterus; the third stage - the synthesis of uterotonic compounds, primarily prostaglandins, oxytocin - the main factors that ensure the development of labor activity.

Of great importance are not only the release of uterotonic compounds before childbirth, but also the pulsating type of their synthesis during childbirth, which ensures the regular nature of labor activity.

As a result of changes occurring in the nervous and humoral

lation, as well as in the uterus itself, an alternating excitation of the centers of sympathetic and parasympathetic innervation is formed:

1) under the influence of mediators of the sympathetic nervous system (norepinephrine and adrenaline), there is a contraction of longitudinally located muscle bundles in the body of the uterus myometrium with simultaneous active relaxation of the circular (transversely) located bundles in the lower segment;

2) in response to the maximum excitation of the center of the sympathetic nervous
system and the release of a large amount of norepinephrine occurs during
awakening of the center of the parasympathetic nervous system;

3) under the influence of the mediator of the parasympathetic nervous system (acetylcholine), the circular muscles contract while relaxing the longitudinal ones;

4) upon reaching the maximum contraction of the circular muscles, the maximum relaxation of the longitudinal muscles occurs;

5) after contraction of the uterus, a period of complete relaxation begins
(pause between contractions), when there is a restorative synthesis of myometrial contractile proteins.

5.2. harbingers of childbirth

The onset of childbirth is preceded by a number of clinical symptoms, united in the concept of "harbingers (precursors) of childbirth." Their appearance indicates the readiness of the pregnant woman for childbirth.

The following signs indicate readiness for childbirth:

Moving the center of gravity of the pregnant woman's body anteriorly, in connection with which
shoulders and head are laid back ("proud tread");

"lowering of the abdomen" of a pregnant woman due to stretching of the lower segment
and insertion of the head in the pelvic inlet, deviation of the uterine fundus
anteriorly as a result of some decrease in the tone of the abdominal press
and the associated relief of breathing (observed 2-3 weeks before
childbirth);

protrusion of the navel;

Unusual sensations of a woman for the last months of pregnancy - increased excitability or, conversely, a state of apathy,
"tides" to the head, which is explained by changes in the central and
autonomic nervous system before childbirth (observed a few days before childbirth);

Decreased body weight of a pregnant woman by 1-2 kg (2-3 days before delivery);

Decreased motor activity of the fetus;

The appearance in the sacrum and lower abdomen of irregular
sensations, first pulling, then cramping;

Isolation from the genital tract of thick viscous mucus (the so-called
mucous plug). Often the secretion of the mucous plug is accompanied by
there is slight bloody discharge due to shallow
tears of the edges of the pharynx;

The cervix becomes "mature" before childbirth. The "maturity" of the cervix is ​​mainly due to morphological changes in collagen and elastin, softening of the connective tissue, an increase in its hydrophilicity, and "disintegration" of muscle bundles. Due to these changes, the neck becomes soft and stretchable, i.e. softens throughout, including the area of ​​​​the internal pharynx (usually softening last), its vaginal part is shortened (up to 1.5-2 cm or less). The cervical canal straightens, smoothly moving into the region of the internal os, through the vaults it is sometimes possible to palpate the sutures, fontanelles or other identifying signs of the presenting part of the fetus. The neck after maturation is located strictly along the longitudinal axis of the pelvis, the external pharynx is located at the level of the ischial bones.

"Maturity" of the cervix is ​​determined in points. Various schemes for determining the "maturity" of the cervix have been proposed. Abroad, the scale of E.N. Bishop (1964), as well as this scale modified by J.E. Burnett (1966), is most widely used.

In our country, the M.S. Burnhill scale modified by E.A. Chernukha is the most common. According to this technique, during vaginal examination, the consistency of the cervix, its length, the patency of the cervical canal and the location of the cervix in relation to the wire axis of the pelvis are determined. Each sign is evaluated in points - from 0 to 2. The total score reflects the degree of "maturity" of the cervix. When assessing 0-2 points, the cervix should be considered "immature", 3-4 points - "not mature enough", 5-8 points - "mature" (Table 5.1).

Table 5.1. Cervical maturity scale

signs	Degree of "maturity", points
Consistency	dense	Softened, but in	Soft
cervix		lasty internal ze-
		va sealed
Neck length	More than 2 cm	1-2 cm	Less than 1 cm or
ki, smoothness			smoothed
Patency	External pharynx for	Canal of the neck	More than one
Nala, yawn	covered, skips	dim for one finger	finger, with
	fingertip	ca, but determined	woman's neck
		compaction in the area	more than 2 cm
		internal os
Neck position	Posteriorly	anterior	Median

5.3. PERIODS OF BIRTH. CHANGES IN MATKE DURING CHILDBIRTH

IN the clinical course of childbirth is divided into three periods: the first period - the opening of the cervix; the second period - the expulsion of the fetus; the third period is successive.

The duration of physiological labor in nulliparas is 12-16 hours, in multiparous - 8-10 hours. In previous guidelines, the following values ​​were given for the course of normal labor: 15-20 and 10-12 hours, respectively.

The first period is the period of cervical dilatation. It begins with the appearance of regular uterine contractions (contractions) and ends with the complete opening of the external cervical os. In primiparous, the duration of the first stage of labor is 10-11 hours, in multiparous - 7-9 hours. At first, contractions are short, weak and rare (after 15-20 minutes). Subsequently, their duration, strength and frequency increase. The interval between two adjacent contractions is called a pause.

In the opening of the cervix, two mechanisms are important: 1) contraction of the muscles of the uterus, 2) action on the cervix from the inside of the fetal bladder or presenting part due to an increase in intrauterine pressure.

The main mechanism for opening the cervix is ​​the contraction of the uterine muscles. The nature of its contraction is due to the peculiarities of the location of muscle fibers in the body of the uterus (mainly longitudinal) and the lower segment (mainly circular). Due to this structure, the body of the uterus and the lower segment perform different functions: the cervix opens, and the body contracts to open the cervix and expel the fetus and placenta.

During each contraction, three processes occur simultaneously in the muscles of the uterus: 1 - contraction of the muscle fibers of the uterus (contraction), 2 - mutual displacement of the fibers relative to each other (retraction), 3 - stretching of the muscle fibers (distraction). In the body of the uterus with a predominance of muscle fibers, contraction and retraction mainly occur. During contractions, muscle elements that are significantly stretched in length shorten, shift, and intertwine with each other during contraction. During the pause, the fibers do not return to their original position, as a result of which a significant part of the muscles is shifted from the lower sections of the uterus to the upper ones. As a result, the walls in the body of the uterus progressively thicken. The retraction regrouping of muscles is closely related to the parallel process of cervical distraction - stretching of the circular muscles of the cervix. The longitudinally located muscle fibers of the body of the uterus at the time of contraction and retraction pull and entail the circularly located muscle fibers of the cervix, contributing to the opening of the cervix.

The mechanism of contractile activity of the uterus during childbirth was studied in detail in 1960 by Caldeyro-Barcia and Poseiro (Montevideo, Uruguay). The researchers introduced into the wall of the uterus of a woman at different levels during labor activity elastic microballoons that respond to muscle contraction, and into the uterine cavity - a catheter that responds to intrauterine pressure. As a result, a hysterogram was recorded - a curve of uterine contractions (Fig. 5.2).

Having registered the amplitude of uterine contraction in its various departments, as well as the total wave of intrauterine pressure in the amnion, the authors put forward provisions that are accepted by obstetricians of all countries. The first provision lies in the law of the triple downward gradient, the second - in the possible quantitative expression of the strength of uterine contractions (Montevideo units, in which uterine activity is expressed). Unit

Rice. 5.2. Triple downward gradient (outline).

Montevideo is the product of the average contraction amplitude and the number of contractions in 10 minutes. Normally, this value is 150-300 IU. The principle of the triple downward gradient is as follows:

The wave of contraction of the uterus has a certain direction - from above
down. Uterine contraction begins in the area of ​​one of the tubal
corners, which is called a pacemaker ("pacemaker"). Then
contraction wave propagates from one uterine angle to the other
gomu, passes to the body with decreasing duration and strength
down to the bottom segment. Contraction speed
uterus is 2-3 cm / s. Through 15-20 with reduction covered
the whole uterus. Despite the fact that various parts of the uterus begin
contract at different times, the maximum contraction of all
muscles occurs simultaneously, which creates optimal conditions
implementation of the contractile activity of the uterus;

The duration of the contraction wave decreases as it travels
from the bottom of the uterus to the lower segment, providing a more pronounced
ny effect of the action of the upper sections of the uterus;

The intensity (amplitude) of uterine contraction also decreases with
as it spreads from the upper sections of the uterus to the lower ones. In body
the force of contraction of the uterus creates a pressure of 50-120 mm Hg. Art., and in
lower segment - only 25-60 mm Hg. Art., i.e. upper divisions
uterus contract 2-3 times more than the lower ones, causing laughing
schenie muscle fibers of the body of the uterus upward.

Rice. 5.3. Increased intrauterine pressure and the formation of a fetal bladder.

Rice. 5.4. The birth canal during the period of exile according to De Lee.

1 - marginal vein; 2 - contraction ring; 3 - bladder; 4 - placenta; 5 - anus; 6 - external pharynx.

With the contraction of the uterus according to the principle of a triple downward gradient in childbirth, the tension of the circular muscles and an increase in intrauterine pressure are created to open the cervix.

During contraction, due to uniform pressure from the walls of the uterus, amniotic fluid, according to the laws of hydraulics, rush towards the lower segment of the uterus (Fig. 5.3). In the center of the lower section of the fetus, there is an internal os of the cervical canal, in which there is no resistance of the walls of the uterus. Amniotic fluid is displaced to the internal pharynx under the influence of increased intrauterine pressure. Under the pressure of amniotic fluid, the lower pole of the fetal egg exfoliates from the walls of the uterus and is introduced into the internal pharynx of the cervical canal. This part of the membranes of the lower pole of the egg, which penetrates along with the amniotic fluid into the cervical canal, is called the fetal bladder. During contractions, the fetal bladder stretches and wedged deeper and deeper into the cervical canal, expanding it from the inside.

Thus, in the mechanism of opening the cervix, the action of two oppositely directed forces matters: 1) attraction from the bottom upwards of the transversely located muscles of the lower segment due to contraction and retraction of the longitudinal muscles of the uterine body and 2) downward pressure due to the fetal bladder or presenting part.

As the cervix dilates, thinning and final formation of the lower segment from the isthmus and cervix occur. The border between the thinned lower segment and the body of the uterus has the form of a furrow and is called the contraction ring (Fig. 5.4). The contraction ring is a functional formation, indicating good

rosha of uterine contractility. The height of the contraction ring above the pubic joint correlates with the degree of cervical dilation: the more the cervix opens, the higher the contraction ring is located above the pubic joint.

The opening of the cervix occurs differently in primiparous and multiparous. In primiparas, the internal pharynx first opens, the neck becomes thin (smoothed), and then the external pharynx opens (Fig. 5.5). In multiparous, the external pharynx opens almost simultaneously with the internal one, and at this time the cervix shortens (Fig. 5.6). The opening of the cervix is ​​considered complete when the pharynx opens up to 10-12 cm. Simultaneously with the opening of the cervix in the first period, as a rule, the advancement of the presenting part of the fetus through the birth canal begins. The fetal head begins to descend into the pelvic cavity with the onset of contractions, being by the time the cervix is ​​fully opened, most often as a large segment at the entrance to the small pelvis or in the pelvic cavity.

With cephalic presentation, as the fetal head advances, separation of amniotic fluid on the anterior and posterior, as the head presses the wall of the lower segment of the uterus against the bone base of the birth canal. The place where the head is covered by the walls of the lower segment is called internal belt of contact(adjacency), which divides the amniotic fluid into the anterior, located below the contact zone, and the posterior - above the contact belt (Fig. 5.7).

The fetal bladder loses its physiological function by the time the cervix is ​​fully dilated. Distinguish a flat bubble in which there is no water. Such a bubble does not form a bulge, and the fetal membranes cover the head of the fetus. A flat amniotic sac can delay labor.

After complete or almost complete opening of the cervix, the membrane of the fetal bladder ruptures under the influence of increased intrauterine pressure, and the anterior waters are poured out (timely outflow of amniotic fluid).

If the fetal membranes do not rupture when the pharynx is fully opened, they must be opened.

If the rupture of the membranes occurs before the onset of labor, then they speak of premature or prenatal, outpouring amniotic fluid; if the waters are poured out after the onset of labor, but before the complete or almost complete opening of the cervix, - about early outflow of water. With excessive density of membranes, the fetal bladder ruptures later than the onset of full disclosure of the cervix - delayed rupture of the membranes. Occasionally, the membranes of the fetal bladder do not rupture, and the fetus is born covered with membranes. - birth in a "shirt". Sometimes the bubble breaks not in the lower pole, near the external pharynx, but higher ("high gap"). In such cases, when the head has entered and advanced, the opening in the fetal bladder closes, and during vaginal examination, a straining fetal bladder is found.

After the outflow of amniotic fluid, contractions may stop or weaken for a while, and then become strong again.

While the fetal bladder is intact, intrauterine pressure on the presenting part of the fetus is even or almost even. After the opening of the fetal bladder, completely different conditions are created, since the intrauterine

Rice. 5.5. Changes in the cervix during the first birth (scheme).

a - the neck is preserved; b - the beginning of smoothing the neck; in - the neck is smoothed; d - complete opening of the cervix: 1 - cervix, 2 - isthmus, 3 - internal pharynx.

Rice. 5.6. Changes in the cervix during repeated births (scheme), a, b - simultaneous smoothing and opening of the cervix; c - full disclosure of the cervix: 1 - cervix, 2 - isthmus, 3 - internal pharynx.

The period of exile lasts from 1 to 2 hours in primiparas, and in multiparous it has a very different duration: from 5-10 minutes to 1 hour.

After the outflow of amniotic fluid, contractions become

less intense, the volume of the uterine cavity is significantly reduced, the walls of the uterus come into close contact with the fetus; contractions intensify. The contraction of the uterus is joined by the contraction of the abdominal press (abdominal wall), diaphragm and pelvic floor muscles, which characterizes the development of attempts. Attempts are a reflex act and occur due to the pressure of the presenting part of the fetus on the nerve endings embedded in the cervix and in the muscles of the pelvic floor. The desire to push is involuntary and uncontrollable. As a result of developing attempts, intrauterine pressure rises even more than in the period of disclosure; their power is aimed at expelling the fetus from the uterus.

This becomes possible due to the fact that the uterus is not only connected to the vagina, but also fixed to the walls of the pelvis by means of a ligamentous apparatus - wide, round and sacro-uterine ligaments, a connective tissue network embedded in the fiber (retinaculum uteri), etc.

As a result of an increase in intrauterine pressure, the fetus makes a series of complex movements, approaches the presenting part to the pelvic floor and exerts increasing pressure on it. Reflexively occurring at the same time, contractions of the abdominal press increase the urge of the woman in labor to push, which are repeated more and more often - every 5-4-3 minutes.

The presenting part of the fetus at the same time stretches the genital gap and is born, behind it the body is born. Together with the birth of the fetus, the back waters are poured out.

After the birth of the fetus, the third, last, period of childbirth begins - the afterbirth.

The third period is successive. This is the time from the birth of the fetus to birth

placenta During this period, detachment of the placenta and membranes from the underlying uterine wall and the birth of the placenta (placenta with membranes and umbilical cord) occur. The follow-up period lasts from 5 to 30 minutes.

Within a few minutes after the birth of the fetus, the uterus is in a state of tonic contraction. The bottom of the uterus is usually located at the level of the navel. The pronounced rhythmic contractions of the uterus that appear soon are called subsequent contractions. Starting with the first subsequent contraction, the placenta separates. The separation of the placenta occurs in the spongy layer of the falling off mucous membrane at the site of its attachment to the uterine wall (placental site).

The placenta during a contraction is practically not capable of contractions, in contrast to the placental site, which, after the expulsion of the fetus and a sharp decrease in the uterine cavity, is significantly reduced in size. Therefore, the placenta rises above the placental site in the form of a fold or tubercle, which leads to disruption of the connection between them and to rupture of the uteroplacental vessels. The blood flowing out at the same time forms a retroplacental hematoma, which is an accumulation of blood between the placenta and the wall of the uterus (Fig. 5.8, a). The hematoma contributes to further detachment of the placenta, which protrudes towards the uterine cavity. Uterine contractions and an increase in retroplacental hematoma, together with the force of gravity of the placenta pulling it down, lead to the final detachment of the placenta from the uterine wall. The placenta, together with the membranes, descends and, with an attempt, is born from the birth canal, turned outward with its fruit surface, covered with a water membrane. This detachment variant is called the Schultze placenta isolation variant.

Along with the described, most common variant of detachment and birth of the placenta, there is a marginal separation of the placenta, which is called the discharge of the placenta according to Duncan (Fig. 5.8, b). The separation of the placenta does not begin from the center, but from the edge. Therefore, the blood flowing from the ruptured vessels flows down freely and, peeling off the membranes on its way, does not form a retro placental hematoma. Until the placenta is completely separated from the uterus, with each new successive contraction, detachment of more and more of its new sections occurs. The separation of the placenta is facilitated by its own mass of the placenta, one of the edges of which hangs down into the uterine cavity. The exfoliated placenta descends and, with an attempt, is born from the birth canal in a cigar-shaped folded form, with the maternal surface facing outward.

The subsequent period is accompanied by bleeding from the uterus. The amount of blood lost during this usually does not exceed 500 ml (0.5% of body weight).

Stopping uterine bleeding from the moment the placenta separates from the uterine wall causes the following:

1) displacement and deformation (twisting, kinking, stretching) of blood vessels as a result of contraction of the uterine muscle, which is a factor in the mechanical stop of bleeding;

2) the originality of the structure of the end sections of the arteries. When separating
placenta, rupture of the uterine vessels occurs at the level of narrowing of the terminal sections of the arteries, the spiral structure of which allows them to contract and move into deeper layers of muscle tissue, where

Rice. 5.8. Different types and stages of separation of the placenta and expulsion of the placenta.

a - the separation of the placenta begins from its center (the variant of the allocation of the placenta according to Schultze); b - separation of the placenta begins from its edge (variant of the allocation of the placenta according to Duncan).

they are subjected to additional compressive action from the contracting muscle of the uterus;

3) thrombus formation, which occurs as a result of the manifestation of the body's defense mechanisms in response to tissue injury. Thrombogenesis leads to stop bleeding in small vessels, mainly capillaries.

In the normal course of the postpartum period, the above factors appear simultaneously.

After the birth of the placenta, the woman who gave birth is called the puerperal.

5.4. MECHANISM OF DELIVERY

In the process of childbirth, when passing through the bone canal (pelvis) and soft tissues of the birth canal of the woman in labor, the fetus performs a set of movements that are called the mechanism (biomechanism) of childbirth. The movements of the fetus during childbirth are determined by the shape of the birth

canal, the size and shape of the fetus, the mobility of its spine, labor activity - expelling forces. The birth canal is formed by the bones of the small pelvis and soft tissues. The bone base of the birth canal during childbirth does not change the spatial relationship, while. soft tissues (deployed lower segment of the uterus, vagina, fascia and muscles lining the inner surface of the small pelvis; muscles of the pelvic floor, perineum) stretch, resist the fetus and take an active part in the mechanism of childbirth.

The bone base of the birth canal due to the sacral

depression has a different configuration in different departments. Promotion of the fetus through the birth canal is usually attributed to the following planes of the pelvis: 1) the entrance to the pelvis, 2) the wide part of the cavity of the small pelvis, 3) the narrow part of the cavity of the small pelvis, 4) the exit of the pelvis.

The natural movements of the fetus are always made strictly in the direction of the wire axis of the pelvis. The wire axis of the pelvis is a line connecting the midpoints of all direct dimensions of the pelvis (the direct dimension of the plane of entry, the wide, narrow part of the cavity of the small pelvis and exit). Due to the curvature of the sacrum and the presence of a powerful layer of muscles of the pelvic floor and perineum, the wire axis of the pelvis resembles the shape of a fishhook (Fig. 5.9).

The fetus also takes part in the mechanism of childbirth. Under the influence of generic forces, a peculiar formation of the fetus occurs: the spine bends, the crossed arms are pressed more tightly to the body, the shoulders rise to the head, and the upper part of the fetus acquires a cylindrical shape, which contributes to its expulsion from the uterine cavity. The greatest importance during the passage of the birth canal (with the longitudinal position of the fetus) are the dimensions of the fetal head. The bones of the fetal skull are connected by sutures and fontanelles, which allows them to move relative to each other and change the configuration of the head. This plasticity allows the fetal head to adapt to the shape and size of the birth canal. The cervical region of the fetus easily bends anteriorly, with difficulty to the right and left. The thoracic region, like the lumbar, bends more to the sides and less - forward and backward.

The mechanism of childbirth is determined by the variant of presentation.

With cephalic presentation, they distinguish flexion(anterior and posterior occiput presentation), which is the most common, and extensor(anterocephalic, frontal, facial presentation) type. The type of presentation is determined by the largest size of the head (pain-

neck segment), with which the head passes in the pelvic cavity. The wired point is located on the presenting part, which, during the advancement of the first, follows strictly in the direction of the wired axis of the birth canal and is the first to be shown from the genital gap.

At the end of pregnancy, the bottom of the uterus, along with the berries in it
tsami as pregnancy develops, begins to experience an increasing
pressure from the diaphragm and abdominal wall. Last thanks
inherent elasticity, low compliance, especially well expressed
in primiparous women, prevents the deviation of the uterine fundus
forward. In this regard, the pressure from the diaphragm applied to
buttocks of the fetus, spreads along its spine and is reported to
dexterity. At the same time, the head is bent and, in a slightly bent state, setting
poured with an arrow-shaped seam in one of the oblique (12 cm) or transverse
(13 cm) size, i.e. the swept seam of the head coincides either with an oblique,
or with the transverse size of the pelvis. *

In multiparous women, the pressure on the fundus of the uterus and the buttocks in it, exerted by the diaphragm, is also reported to the head of the fetus and the anterior abdominal wall. However, unlike primiparas, this pressure is not properly counteracted by the overstretched abdominal wall. Therefore, in multiparous women with a relaxed anterior abdominal wall, the bottom of the uterus deviates anteriorly, and the head remains mobile over the entrance to the pelvis until the onset of childbirth and even in most cases in their first period.

When the head is inserted into the plane of the entrance to the pelvis, the swept seam can be located in the transverse or in one of the oblique, or in a slightly oblique size. In relation to the swept suture to the pubic joint and the promontory (promontorium), axial, or synclitic(Fig. 5.10), and off-axis, or asynclistic(Fig. 5.11, a, b), head insertion. With synclitic insertion, the head is perpendicular to the plane of the entrance to the small pelvis, and the sagittal suture is located at the same distance from the pubic symphysis and the promontory. With asynclitic insertion, the vertical axis of the fetal head is not strictly perpendicular to the plane of the entrance to the pelvis, and the sagittal suture is located closer to the promontory - anterior asynclitism (the parietal bone facing anteriorly is inserted) or closer to the pubic articulation - posterior asynclitism (the parietal bone facing backwards is inserted ). In normal labor, there is either synclitic insertion of the head or slight anterior asynclitism. Later, during the physiological course of childbirth, when the direction of pressure on the fetus changes during contractions, asynclitism is eliminated.

5.4.1. The mechanism of labor in anterior occipital presentation

The mechanism of labor begins in that plane of the pelvis, in which the fetus encounters an obstacle as it progresses.

Some advancement of the head is observed during pregnancy. With the onset of childbirth, the forward movement of the head resumes at the first contractions. In the case of normal delivery, when the head moves from the wide to the narrow part of the pelvic cavity, the fetus encounters an obstacle. To overcome the obstacle encountered by the head, uterine contractions alone are not enough. This requires attempts, during which, due to pressure, the fetus moves towards the exit from the birth canal. Despite the fact that the mechanism of childbirth can begin in the period of disclosure, more often it occurs in the period of exile, when the head moves from the wide to the narrow part of the pelvic cavity.

During the entire period of exile, the fetus and the birth canal continuously influence each other. At the same time, the fetus tends to stretch the birth canal according to its shape, which tend to tightly cover the fetus with the surrounding back waters and adapt to its shape. As a result of the interaction of the fetus and the birth canal, the shape of the fetal egg (fetus, back water, placenta) and the birth canal gradually come into full compliance with each other. The walls of the birth canal tightly cover the entire fetal egg, with the exception of the lowest segment (segment) of the head.

Fig.5.12. The mechanism of childbirth in the anterior view of the occipital presentation.

a - the first moment: 1 - flexion of the head, 2 - view from the side of the exit of the pelvis (sagittal suture in the transverse dimension of the pelvis); b - second moment: 1 - internal rotation of the head, 2 - view from the side of the exit of the pelvis (sagittal suture in the right oblique size of the pelvis); c - completion of the second moment: 1 - internal rotation of the head is completed, 2 - view from the side of the pelvis (the sagittal suture is in the direct size of the pelvis).

Rice. 5.12. Continuation.

d - the third moment: extension of the head after the formation of a fixation point (the head with the area of ​​the suboccipital fossa came under the pubic arch); e - the fourth moment: external rotation of the head, the birth of the shoulders (the anterior shoulder is delayed under the symphysis); e - the birth of the shoulders, the back shoulder rolls out over the crotch.

As a result, favorable conditions are created for the expulsion of the fetus from the birth canal.

In the anterior view of the occipital presentation, four main points of the mechanism of childbirth are distinguished (Fig. 5.12, a-g).

First moment- flexion of the head (flexio capitis). Under the influence of intrauterine and intra-abdominal pressure, the cervical part of the spine bends, the chin approaches the chest, the back of the head drops down. As the back of the head lowers, the small fontanel is set below the large one, gradually approaches the median (wire) line of the pelvis and finally becomes the lowest part of the head - the wire point.

Flexion of the head allows it to pass through the cavity of the small pelvis in the smallest or close to it size - small oblique (9.5 cm). However

with a normal ratio of the sizes of the pelvis and the head, there is no need for maximum flexion of the head: the head bends as much as necessary to pass from the wide to the narrow part of the pelvic cavity.

second moment- internal rotation of the head (rotatio capitis interna). The fetal head, during its translational movement in the pelvic cavity, when it passes from the wide to the narrow part, encountering an obstacle to further advancement, simultaneously with bending, begins to rotate around its longitudinal axis. At the same time, the back of the head, sliding along the side wall of the pelvis, approaches the pubic joint, while the anterior section of the head departs to the sacrum. This movement is easy to detect by observing the change in the position of the swept seam (see Fig. 4.15, A1, B1, C1). The sagittal suture, located before the described rotation in the cavity of the small pelvis in the transverse or one of the oblique dimensions, subsequently passes into the direct dimension. The rotation of the head ends when the sagittal suture is set in the direct size of the exit, and the suboccipital fossa is set under the pubic joint.

This rotation of the head is preparatory to the third moment of the birth mechanism, which without it would have taken place with great difficulty or not at all.

Third moment- extension of the head (deflexio capitis). The fetal head continues to move through the birth canal and at the same time begins to unbend. Extension during the physiological course of childbirth occurs at the outlet of the pelvis. Extension begins after the suboccipital fossa rests against the lower edge of the pubic articulation, forming a fixation point (hypomochlion). The head rotates with its transverse axis around the fixation point (the lower edge of the pubic symphysis) and in a few attempts it fully unbends and is born. At the same time, the parietal region, forehead, face and chin sequentially appear from the genital slit. The birth of the head through the vulvar ring occurs with its small oblique size.

Fourth moment- internal rotation of the body and external rotation of the head (rotatio trunci interna seu rotatio capitis externa). During the extension of the head, the fetal shoulders are inserted into the transverse dimension of the entrance or into one of its oblique dimensions as the head advances. In the exit plane of the pelvis, following it, the shoulders of the fetus spirally move along the pelvic canal. With their transverse size, they pass from the transverse to the oblique, and when they exit, into the direct size of the pelvis. This rotation is transmitted to the born head, while the nape of the fetus turns to the left (in the first position) or right (in the second position) thigh of the mother. The front shoulder turns to the pubic joint, the back - to the sacrum. Then the shoulder girdle is born in the following sequence: first, the upper third of the shoulder, facing anteriorly, and then, due to lateral flexion of the spine, the shoulder, facing backwards. Next, the entire body of the fetus is born.

All of the listed moments of the mechanism of childbirth are performed with the translational movement of the fetal head, and there is no strict distinction between them (Fig. 5.13).

The first moment of the mechanism of childbirth is not limited to head flexion alone. It is also accompanied by translational movement, its advancement along the birth canal, and later, when flexion ends, and the beginning of the internal rotation of the head. Hence,

The second moment of the labor mechanism is a combination of translational and rotational movements. Along with this, at the beginning of the internal turn, the head finishes bending, and towards the end of the turn, it begins to unbend. Of all these movements, the most pronounced is the rotation of the head, so the second moment of the birth mechanism is called "internal rotation of the head."

The third moment of the mechanism of childbirth is composed of translational movement and extension of the head. However, along with this, almost until birth, the head continues to make an internal turn. At this point in the mechanism of childbirth, the most pronounced is the extension of the head, as a result of which it is called "extension of the head."

childbirth proceed in the presence of a formed " generic dominant", which is a single dynamic system that combines both higher centers of regulation (central and autonomic nervous system, hormonal regulation) and executive organs (uterus and fetoplacental complex).

Normal birth act is determined by the involvement of the cerebral cortex in the dominant process, in particular the temporal lobes of the cerebral hemispheres, as well as a significant increase in interhemispheric connections that facilitate the coordination of somatic functions.

An important part of the coordination centers of labor activity is located in the subcortical structures of the brain: in the hypothalamus - in the amygdala nuclei of the limbic complex, the pituitary gland.

Before childbirth the inhibitory processes in the cerebral cortex gradually increase and the excitability of the subcortical structures that regulate labor activity increases. At the same time, the excitability of the peripheral parts of the nervous system increases, in particular interoreceptors that transmit excitation from the genital organs. Afferent impulsation from the uterus, which forms unconditioned reflexes associated with the birth act, is enhanced by maturity fetoplacental complex. Before childbirth, it exceeds the sensitivity threshold of perceiving subcortical structures, promoting childbirth.

The severity of the reflex reactions underlying childbirth depends on the tone of the various parts of the autonomic nervous system, innervating the uterus. All parts of the uterus (body, lower segment) have a double autonomic innervation. Adrenergic innervation prevails in the longitudinally located muscle bundles in the body of the uterus. Cholinergic innervation observed mainly in circular and spirally arranged muscle fibers, located mainly in the lower segment of the uterus. There are located M-cholinergic receptors. Adrenoreceptors in the uterus are represented by two types: ap and a2-adrenergic receptors. Impact on P2-adrenergic receptors causes a decrease in tone, excitability and contractile activity of the uterus. Before childbirth, the number and activity of oq-adrenergic receptors and M-cholinergic receptors increase.

Vegetative regulation of uterine contractions is carried out through mediators, the main of which are acetylcholine, adrenalin And norepinephrine.

Acetylcholine has a stimulating effect on the muscles of the uterus.

Before childbirth and during childbirth, a high level of the active form of acetylcholine is observed in the blood plasma of pregnant women with a simultaneously low activity acetylcholinesterase.

Catecholamines(adrenalin, norepinephrine) mediate adrenergic effects on the myometrium by interacting with ap and p 2 -adrenergic receptors of smooth muscle cells. The activating effect of catecholamines is mainly realized by their action on adrenergic receptors of smooth muscle cells of the myometrium. The inhibitory effect of catecholamines on the myometrium is associated with their interaction with p 2 -adrenergic receptors of smooth muscle cells.

Features of the nervous regulation of labor activity are associated with hormonal changes before childbirth. Only in the presence of certain hormonal ratios are possible reflex excitability of the uterus and those neurophysiological changes in which it is able to contract regularly throughout childbirth. Of the entire complex of regulatory components duplicating each other during the period preparation for childbirth, of particular importance is the increase in the synthesis of estrogens (mainly their active fraction - estradiol) against the background of a decrease in the level of the main pregnancy hormone - progesterone, which blocks the contraction of the muscles of the uterus. Before delivery, the content of progesterone and its metabolites in the blood and urine decreases and the ratio of estriol / pregnandiol in the urine is 1:1 (during pregnancy 1:100).

Under the influence estrogen the following changes occur:

Increases blood flow in myometrium, intensity redox processes, synthesis of myometrial contractile proteins ( actomyosin), energy compounds ( ATP, glycogen) and uterotonic prostaglandins;

Increases the permeability of cell membranes for ions (K + , Ca, Na), leading to a decrease in the resting membrane potential, an increase in the sensitivity of myometrial cells to irritation;

calcium is deposited in the sarcoplasmic reticulum;

increases the activity of phospholipases and the rate of " arachidonic cascade with the formation of prostaglandins.

These changes will intensify contractility of the uterus, acceleration of "maturation" of her neck.

In the development of labor, in addition to estrogens, a key role is played by prostaglandins , which, according to modern concepts, are the main labor initiation stimulants. The site of prostaglandin synthesis in the pregnant uterus is the fetal ( amnion And chorion) And decidua. At the same time, prostaglandin E (PGE) is formed in the amnion and chorion, and both PGE and nrF 2a (maternal) are synthesized in the decidua and myometrium. The production of prostaglandins at the end of pregnancy is due to the processes of aging and degeneration of the structural elements of the placenta, decidua, amnion, since these processes are associated with the activation of phospholipases and the formation of arachidonic acid, and subsequently - prostaglandins.

Prostaglandins stimulate the following processes :

Formation on the membrane of cc-adrenergic receptors and receptors for other uterotonic compounds (acetylcholine, oxytocin, serotonin);

Ensuring automatic contraction of the uterus (contractions);

inhibition of oxytocinase production.

Along with an increase in the synthesis of estrogens and prostaglandins, an increase in the activity of other neurohumoral mediators and hormones ( oxytocin,serotonin, kinin, histamine).

Oxytocin is an important regulator contractile activity of the uterus. It is considered by many authors as a triggering factor in the development of labor activity. Oxytocin It is a synergist of acetylcholine and prostaglandins. Its plasma concentration increases with increasing gestational age. The effect of oxytocin on the contractile activity of the uterus depends on the hormonal background, primarily on the optimal level of estrogen, as well as the functional state of the uterus, its readiness for spontaneous activity.

The action of oxytocin is associated with the following processes :

Strengthening of the membrane potential and increased excitability of the muscle cell;

increase in the rate of binding of acetylcholine by receptors myometrium and freeing it from its bound state;

excitation of ai-adrenergic receptors;

inhibition of cholinesterase activity.

As a result of oxytocin increased tone of the uterus, stimulated frequency and amplitude of contractions.

Serotonin has a pronounced effect on the state and function of myometrial cells, inhibits the activity of cholinesterase and enhances the action of acetylcholine, promotes the transfer of excitation from the motor nerve to the muscle fiber.

The action of serotonin on the uterus can be carried out in two ways: directly on the myometrium through a-receptors and through the central nervous system by increasing the production of oxytocin by the neurohypophysis.

kinins increase the contractility of the uterus by increasing the speed of blood flow in it.

Of certain importance in the development of labor activity is histamine , which promotes the production of oxytotic substances by the pituitary gland.

There is an assumption that changes in hormonal relationships in the mother before childbirth are closely related to the degree of maturity of hormonal regulation in the fetus, which is genetically determined by the completeness of the processes of its growth and development. Maturity matters first. epiphysis-hypothalamic-pituitary system fetus.

The effect of fetal hormones on the preparation and onset of labor consists of the following points:

With an increase in the level of fetal corticotropin in the mother's blood, the content of estradiol increases and the amount of progesterone, hCG And choriomammotropin(placental lactogen);

released before birth in the fetus oxytocin acts similarly to maternal oxytocin;

prenatal level melatonin in the blood of the fetus increases, and in the mother - decreases. These changes in the concentration of melatonin contribute to the restructuring steroid hemostasis and the formation of an estrogen background in the body of a pregnant woman. Melatonin changes the ratio of prolactin / foliculotropin in the direction of increasing the last two. The result is an increase in the synthesis estriol. Along with this, a decrease in the level of melatonin in the mother's blood leads to the release of leukotrienes(slow-reacting substances of anaphylaxis), which in turn leads to the activation of keylon activity and inhibition of a further increase in the mass of the fetus, its organs and tissues and contributes to the activation of the mechanisms of preparing the body of a pregnant woman for childbirth. Simultaneous suppression of the synthesis of immunosuppressants prolactin and hCG leads to an increase in transplantation immunity and stimulates the rejection of the fetus as an allograft;

· ischemia of the membranes of the fetal egg before childbirth, due to an increase in intrauterine pressure, activates the "arachidon cascade" with the release of uterotonic prostaglandins.

Along with changes in the nervous and humoral regulation before childbirth, significant changes occur in the reproductive system, including the uterus.

The contraction of the muscles of the uterus, as well as other organs (heart, blood vessels), is based on the process of converting chemical energy into mechanical energy.

Of particular importance for the onset of labor are the following processes occurring in the uterus:

An increase in the intensity of metabolic processes in the myometrium, the rate of oxygen consumption (3.5 times), the content of the contractile protein actomyosin (by 25%), glycogen, glutathione, phosphorus compounds (ATP, creatine phosphate, phosphocreatinine), which play an important role in the energy processes of muscle fabrics;

Changes in the ratio between muscle and connective tissue towards a sharp predominance of the first of them, especially in the body of the uterus.

As a result of changes occurring in muscle cells, the membrane potential decreases, their excitability increases, spontaneous activity increases, sensitivity to contractile substances increases.

WITH onset of labor a group of cells is formed in the uterus, in which excitation initially occurs, subsequently spreading to the entire uterus. This area is called the pacemaker (" pacemaker"). It is located in the bottom of the uterus, closer to the right corner.

Changes in the ratio of hormones and biologically active substances that affect the excitability and contractile activity of the uterus before childbirth take place in several stages: the first stage is characterized by the state of maturity of the hormonal regulation of the fetus; the second stage - activation of estrogens and changes in the uterus; the third stage - the synthesis of uterotonic compounds, primarily prostaglandins, oxytocin - the main factors that ensure the development of labor activity.

Not only the release of uterotonic compounds before childbirth is important, but also the pulsating type of their synthesis during childbirth, which ensures regular nature of labor activity.

As a result of changes occurring in the nervous and humoral regulation, as well as in the uterus itself, an alternating excitation of the centers of sympathetic and parasympathetic innervation is formed:

1) under the influence of mediators of the sympathetic nervous system ( norepinephrine And adrenalin) there is a contraction of longitudinally located muscle bundles in the body of the uterus of the myometrium with simultaneous active relaxation of the circularly (transversely) located bundles in the lower segment;

2) in response to the maximum excitation of the center of the sympathetic nervous system and the release of a large amount of norepinephrine, the center of the parasympathetic nervous system is excited;

3) under the influence of the mediator of the parasympathetic nervous system ( acetylcholine) the circular muscles contract while simultaneously relaxing the longitudinal ones;

4) upon reaching the maximum contraction of the circular muscles for
the maximum relaxation of the longitudinal steps;

5) after contraction of the uterus, a period of complete relaxation begins ( pause between contractions) when it happens reductive synthesis of myometrial contractile proteins.