Weak labor activity - causes, symptoms and consequences. Weak labor activity: a real danger or a convenient excuse for doctors

Weakness of labor activity is a pathological condition that is characterized by a decrease and weakening of contractions, as well as a slow opening of the cervix. At the same time, the woman in labor gets very tired and loses strength.

Weak labor activity is primary and secondary.

Primary is a decrease in uterine activity that occurs at the very beginning of childbirth. The frequency of occurrence is 5-7% of the number of all births.

Secondary - this is a decrease in the duration, intensity and frequency of contractions after a favorable onset of the course of labor. At the same time, the rate of opening and smoothing of the cervix also decreases, and the movement of the fetus through the birth canal slows down. It occurs in 2-3% of births.

Causes

The risk group includes pregnant women who have a history of:

• childhood infections (rubella, chickenpox, measles);
• late onset of the first menstruation (menarche), after 15-16 years;
• menstrual irregularities;
• infantilism (small uterus);
• anomalies in the development of the uterus;
• inflammatory diseases of the reproductive system;
• scar on the uterus (after caesarean section, removal of fibroids, ectopic pregnancy, etc.);
• abortions;
• large fruit;
• a large number of births;
• diseases with metabolic disorders.

The reason for the weakness of the birth process can be mechanical obstacles (narrow pelvis, breech presentation of the fetus, inelasticity of the cervix). The age of the pregnant woman also plays a role - women under the age of 17 and over 30 are more prone to anomalies in labor. Obstetric reasons include:

• prenatal outpouring of water;
• multiple pregnancy;
• post-term pregnancy or, conversely, premature birth;
• large size of the fetus;
• transverse or oblique position of the fetus;
• pelvic presentation of the fetus;
• fear of childbirth, great loss of strength.

The reasons may be from the side of the fetus:

• intrauterine infection;
• malformations and anomalies of development;
• Rhesus conflict;

Most often, for the development of weak labor activity, several reasons or a combination of them are needed.

Signs of weak labor activity

Primary weakness of labor can be manifested by such symptoms:

• contractions become less sensitive, rare or short;
• the smoothing of the cervix and the opening of the uterine pharynx slow down or stop (the doctor determines during a vaginal examination);
• the presenting part of the fetus (head or pelvic end) remains permanently movable or pressed against the entrance to the small pelvis;
• the long course of the first stage of labor (for primiparous more than 12 hours, for multiparous more than 10 hours) and, as a result, the fatigue of the woman in labor;
• possible untimely discharge of amniotic fluid.

Norms of disclosure and contractions in the first stage of labor

Normally, in a primiparous woman, the cervix of the uterus opens by 1-1.2 cm per hour, in a multiparous woman - 1.5-2 cm per hour. If the cervix opens more slowly, then this may indicate the development of primary weakness of labor activity.

In the first period, the normal duration of contractions is 20-30 seconds, and the interval between them is 7-10 minutes. With the pathology of labor activity, their duration decreases, and the interval between them increases.

Secondary generic weakness is characterized by a longer period of expulsion of the fetus (more than 1-1.5 hours). This is due to the weakening or cessation of contractions, which at the beginning were intense, rhythmic and prolonged. At this point, the progress of the fetus along the birth canal slows down or stops altogether.

Diagnostics

Primary weakness of labor activity is diagnosed on the basis of:

• decrease in uterine activity (contractions weaken, become rare);
• reducing the speed of smoothing the neck and opening the uterine pharynx;
• prolonged standing of the presenting part of the fetus at the entrance to the small pelvis;
• increase in delivery time.

The diagnosis is also made on the basis of partogram data, if there is no dynamics of cervical dilatation within two hours.

Partogram - a description of childbirth in a graphical way, which displays data on cervical dilatation, fetal progress, pulse, blood pressure, fetal heartbeat, amniotic fluid, contractions, etc.

Secondary birth weakness is diagnosed on the basis of the clinical picture and partogram data. In addition, it is necessary to monitor the condition of the fetus (listen to the heartbeat, install a CTG sensor), as there is a risk of developing hypoxia. After establishing the diagnosis, obstetricians need to decide on the tactics of childbirth.

Weakness of labor must be distinguished from the following pathologies:

• pathological preliminary period (chaotic false contractions with an immature cervix);
• discoordinated labor activity (violation of the contractile activity of the uterus, it is extremely painful; it is very rare);
• clinically narrow pelvis (mismatch between the size of the pelvis and the head of the fetus).

Treatment and delivery in case of weak labor activity

There are several methods of medical care. The doctor makes a decision depending on the causes of the pathology and the condition of the woman in labor and the fetus. If labor is prolonged and life-threatening, labor is induced or an emergency caesarean section is performed. Methods of medical care:

1. Stimulation of childbirth without medication. Labor activity can be strengthened by the procedure of amniotomy (opening of the fetal bladder), which allows you not to use drugs. Do not be afraid, amniotomy is completely painless.

2. Medicinal stimulation. It is carried out in case of ineffectiveness of the amniotomy. It can be carried out with the help of strong analgesics, which induce drug-induced sleep to relax and rest the woman in labor. Stimulation with oxytocin and prostaglandins is performed intravenously.

3. Cesarean section. An emergency operation is performed in case of ineffective stimulation and in case of a threat to life for the woman in labor or the fetus.

drug sleep

For therapeutic sleep, sodium oxybutyrate and glucose are administered, performed by an anesthesiologist. In his absence, the obstetrician introduces promedol, relanium, atropine and diphenhydramine. Medication sleep allows a woman in labor to rest for 2-3 hours and gain strength, and also helps to intensify contractions. If there is an indication for an emergency caesarean section, then there is no need for therapeutic sleep.

After the woman has a rest, the doctor needs to assess her condition and the fetus, as well as the degree of opening of the uterine pharynx. After that, a hormonal-energy background is created with the help of:

• ATP, riboxin, cocarboxylase;
• 40% glucose solution;
• calcium preparations (to enhance uterine contraction);
• vitamins: B1, B6, E, ascorbic acid;
• piracetam (to improve uterine circulation).

Amniotomy

Opening the fetal bladder promotes the production of prostaglandins, which stimulate contractions. It is performed when the cervix is ​​dilated by 3-4 cm. 2-3 hours after the procedure, the doctor needs to assess the state of the dynamics of cervical dilatation, and also decide on the use of reducing drugs.

Medical stimulation

When stimulated with drugs, oxytocin and prostaglandins are used.

Oxytocin is administered intravenously through a drip. It provokes increased contractions and the production of prostaglandins. Oxytocin is administered when the uterine os opens by 5-6 cm or more, only after amniotomy or spontaneous discharge of amniotic fluid.

Prostaglandin E2 contributes to the development of normal contractions. The drug also accelerates the maturation of the cervix and its opening, while not disturbing the uteroplacental circulation. The drug is administered similarly to oxytocin. It is used until the opening of the uterine os by 2-3 cm with an insufficiently mature cervix.

Prostaglandin F2a (enzaprost or dinoprost) is used when opening the uterine os by 5 cm or more. Effects of the drug: stimulation of contractions, narrowing of blood vessels, increased blood clotting. Therefore, it is contraindicated in preeclampsia and blood diseases. Prostaglandin F2a is administered intravenously using a drip system.

With drug stimulation, it is mandatory to prevent fetal hypoxia every 3 hours. For this, a 40% glucose solution + ascorbic acid + eufillin, sigetin or cocarboxylase is injected intravenously. It also shows the inhalation of humidified air.

C-section

If all of the above methods were ineffective or there are additional indications, then a caesarean section is performed.

Contraindications for labor stimulation

• narrow pelvis (anatomical and clinical);
• the presence of a scar on the uterus;
• women with a history of more than 5-6 births;
• incorrect position and presentation of the fetus;
• life threatening for the mother and fetus.

Possible Complications

In the case of an incorrect choice of a delivery strategy with weak labor activity, the following complications are possible:

• abuse of stimulant drugs can lead to discoordinated labor and fetal hypoxia.
• prolonged standing of the presenting part of the fetus in one plane of the small pelvis can lead to compression of the soft tissues, in which there is a risk of urogenital fistulas. On the part of the fetus, this can lead to impaired cerebral circulation and cerebral hemorrhage.
• in women with weakness of labor in the postpartum period, there is a risk of hypo- and atonic bleeding, infectious diseases.

Forecast

With adequate medical care, the prognosis for the woman and the fetus is favorable. Much depends on the psychological state of the woman, there is no need to panic and be afraid, it is better to listen to the recommendations of the obstetrician. Serious complications are rare.

Some research on pregnancy

- insufficient in strength, duration and frequency of contractile activity of the uterus, due to its hypotonic dysfunction. The weakness of labor activity is manifested by rare, short and ineffective contractions, slowing down the opening of the cervix and advancement of the fetus. Pathology is diagnosed through observation, cardiotocography, vaginal examination. In the treatment of weakness of labor activity, rhodostimulation is used; according to indications, a caesarean section is performed.

The weakness of labor activity may be due to the late or young age of the primipara; preeclampsia; premature birth or post-term pregnancy; overstretching of the uterus with multiple pregnancy, large fetus, polyhydramnios; disproportion between the size of the fetus and the pelvis of the woman in labor (narrow pelvis); early discharge of water. Placenta previa, the course of pregnancy in conditions of chronic placental insufficiency, fetal pathology (hypoxia, anencephaly, etc.) can lead to the development of weakness in labor activity.

In addition, the weakness of labor activity can be aggravated by the asthenization of a woman (overwork, excessive mental and physical stress, poor nutrition, insufficient sleep); fear of the woman in labor, uncomfortable environment, inattentive or rude service. The weakness of labor activity is often a direct continuation of the pathological preliminary period of childbirth.

Types of weakness of labor activity

According to the time of occurrence, primary weakness of labor activity and secondary are distinguished. The primary weakness is considered a situation in which, from the very beginning of childbirth, insufficiently active (weak in strength, irregular, short) contractions develop. They speak of secondary weakness if there is a weakening of contractions at the end of the 1st or the beginning of the 2nd period of labor after the initially normal or violent nature of labor.

The varieties of weakness of labor activity include segmental and convulsive contractions. Convulsive contractions are characterized by prolonged (more than 2 minutes) uterine contractions. With segmental contractions, not the entire uterus contracts, but its individual segments. Therefore, despite the continuity of segmental contractions, the effect of them is extremely small. Determination of the clinical form of weakness of labor activity allows you to choose differentiated tactics in relation to the treatment of disorders.

Symptoms of weakness in labor

Clinical manifestations of the primary weakness of labor activity are: decreased excitability and tone of the uterus; frequency of contractions - 1-2 within 10 minutes; the duration of contractions is not more than 15-20 seconds; amplitude (strength) of contractions of the myometrium - 20-25 mm Hg. Art. The period of contraction of the uterus is short, the period of relaxation is 1.5-2 times longer. There is no increase in intensity, amplitude, frequency of contractions over time.

Contractions with primary weakness of labor activity can be regular or irregular, painless or slightly painful. The course of structural changes in the cervix (shortening, smoothing and opening of the cervical canal and uterine os) is slowed down. The weakness of the contractile activity of the uterus often accompanies the period of exile, as well as the subsequent and early postpartum period, which leads to hypotonic bleeding. The primary weakness of labor activity leads to a delay in the duration of labor, fatigue of the woman in labor, untimely discharge of amniotic fluid, lengthening of the anhydrous period.

In the case of secondary weakness of labor activity, initially effective contractions weaken, become shorter and less frequent, up to a complete cessation. This is accompanied by a decrease in the tone and excitability of the uterus. The opening of the uterine os can reach 5-6 cm without further progression; the progress of the fetus through the birth canal stops. The danger of weak labor is an increased risk of ascending infection of the uterus, the development of fetal asphyxia or intrauterine death. With prolonged standing of the fetal head in the birth canal, birth injuries of the mother (hematomas, vaginal fistulas) may develop.

Diagnosis of weakness of labor activity

To determine the nature of labor activity, a clinical assessment of the effectiveness of contractions, uterine tone, and labor dynamics is carried out. During childbirth, monitoring of uterine contractions (tocometry, cardiotocography) is carried out; analysis of the frequency, duration, strength of contractions and their comparison with the norm. So, in the active phase of the 1st period, contractions lasting less than 30 seconds are considered weak. and intervals over 5 minutes; for the 2nd period - shorter than 40 sec.

With the weakness of labor activity, the opening of the cervix occurs by less than 1 cm per hour. The degree and speed of opening are assessed during the vaginal examination, as well as indirectly - by the height of the contraction ring and the advancement of the head. Weakness of labor activity is said if the 1st stage of labor lasts more than 12 hours for primiparas, and more than 10 hours for multiparous ones. Weakness of labor forces should be differentiated from discoordinated labor activity, since their treatment will be different.

Treatment of weakness in labor

The choice of treatment regimen is based on the causes, the degree of weakness of labor, the period of labor, the assessment of the condition of the fetus and mother. Sometimes, to stimulate the intensity of contractions, it is enough to catheterize the bladder. If the weakness of labor activity is caused In the process of conducting pregnancy by an obstetrician-gynecologist, it is necessary to assess risk factors for the development of weakness of labor activity, and if such factors are identified, preventive medication and psychophysical training should be carried out. The weakness of labor activity almost always leads to a deterioration in the condition of the fetus (hypoxia, acidosis, cerebral edema), therefore, simultaneously with labor stimulation, prevention of fetal asphyxia is carried out.

Often the cause of complications in the period of delivery is a weak labor activity. As a result of such a violation, negative consequences can occur both during childbirth and in the postpartum period. Let us consider this phenomenon in more detail, find out: what does weak labor activity mean, highlighting the causes, signs and methods of struggle.

"Weak generic activity" - what is it?

Before considering the pathology, let's deal with the definition and find out: what is weak labor activity in women and when it occurs. Obstetricians talk about such a violation when the contractile activity of the uterus does not have the necessary strength to expel the fetus. This is due to a change in the duration and frequency of labor pains. They are rare, short, ineffective. As a result, the process of opening the cervix slows down, the rate of advancement of the fetus decreases, and the development of weak labor activity is observed.

Weak labor activity - causes

Due to the fact that often the violation is provoked simultaneously by several factors, it is problematic to establish the causes of weak labor activity in women in a particular case. At the same time, doctors identify several groups of factors that cause a violation of the delivery process. Among those:

1. Obstetric complications:

• early effusion;
• discrepancy between the size of the fetal head and the size of the pelvis of the woman in labor;
• the presence of dystrophic and structural changes in the walls of the uterus (the presence of abortions, a history of curettage, endometriosis, uterine fibroids);
• rigidity of the muscle layer of the neck (non-extensibility of the organ due to previous operations, diseases);
• incorrect placenta previa;
• gestosis.

2. Pathologies of the reproductive system:

• congenital anomalies in the structure of the uterus (bicornuate, saddle-shaped);
• sexual infantilism (underdevelopment of the reproductive organs);
• chronic inflammatory processes in the uterus;
• violation of the menstrual cycle;
• diseases of the endocrine system leading to hormonal imbalance.

3. Extragenital diseases:

• chronic diseases of internal organs (pathologies of the liver, kidneys, heart);
• disruption of the endocrine system (obesity, hypothyroidism, diabetes mellitus).

4. Factors due to the baby:

• intrauterine infection;
• intrauterine growth retardation;
• delayed pregnancy;
• premature delivery;
• fetal hypoxia;

5. Iatrogenic causes:

• long-term use of labor-stimulating agents;
• neglect of anesthetic measures during childbirth;
• unreasonable amniotonia (opening of the fetal bladder by a doctor);
• private vaginal examinations.

Is weak labor activity inherited?

The belief of some expectant mothers regarding the fact that weak labor activity is inherited is erroneous. This pathology has no connection with the genetic apparatus, therefore, it cannot be inherited from mother to daughter. In most cases, a violation occurs when the delivery process itself is not properly managed, and the woman does not comply with the requirements of the obstetrician. Evidence of the absence of a connection between the disorder and heredity is the high frequency of its development during childbirth.

Weak labor activity at first birth

In order to understand why there is a weak labor activity, it is necessary to briefly consider the mechanism of childbirth itself. So after the opening of the cervix, the end of the first period, the exile phase begins. More often, the weakness of labor activity occurs at the stage of disclosure, the gradual increase in the lumen of the cervical canal is suspended. As a result, this period of childbirth is delayed, the woman in labor loses strength, gets very tired. Given these features, among the causes of weak labor activity at the first delivery, one can single out:

• improper prenatal preparation of a pregnant woman;
• violation of the algorithm for conducting the first stage of childbirth - excessive drug stimulation of the process;
• non-compliance by the woman in labor with the instructions of obstetricians.

Weak labor activity during the second birth

Talking about what is associated with weak labor activity during repeated childbirth, doctors put forward a violation of the delivery process in the first place. A feature of the second and subsequent births is the shortening of the period of disclosure and exile. Contractions grow, become intense after a short time. At the same time, the absence of a number of competent medical staff capable of providing maternity benefits increases the risk of a decrease in the activity of uterine structures. The woman in labor herself loses strength, cannot productively push - a secondary weakness.

Weak labor activity - signs

The diagnosis of "weak labor activity" is made exclusively by the obstetrician taking delivery. At the same time, doctors evaluate the nature of contractions, the speed of cervical dilatation. Directly lengthening the period of disclosure is a symptom of a violation. At the same time, there are signs of weak labor activity:

• short duration and low intensity of contractions;
• a decrease in the rate of advancement of the fetus through the birth canal;
• increase in intervals between contractions;
• severe fatigue of the woman in labor;
• development of fetal hypoxia.

Weak labor activity - what to do?

Having experienced this violation once, women preparing to become a mother for the second time are often interested in the question of how to intensify contractions with weak labor activity. Initially, it all depends on the mood of the pregnant woman herself, her readiness for childbirth. Fears, overwork, fear for the future baby - have a bad effect on the process of delivery.

In order to reduce the risk of developing weak labor, doctors recommend expectant mothers:

• calm down using non-drug methods (massage, proper breathing);
• in the period of disclosure, it is necessary to be active - walking, light jumps in place help the cervix;
• if a woman is forced to take a horizontal position (a dropper is connected), it is necessary to lie on the side on which the back of the fetus is located.
• you should monitor the condition of the bladder - it must be emptied every 2 hours.

Preparations for weak labor activity

With such a violation as weak labor, how to intensify contractions, stimulate the process, doctors decide based on the degree of pathology, the condition of the woman in labor. The main non-drug method of activation of labor activity is amniotomy - a violation of the integrity, opening, of the fetal bladder. Manipulation is carried out with the opening of the cervix by 2 cm or more. If there is no effect within 2-3 hours, if weak labor activity does not disappear, they resort to drug intensification of childbirth. Among the drugs used:

1. Oxytocin. Enter drip, intravenously. They begin to use it when the cervix is ​​dilated by 5 cm or more and after the opening of the fetal bladder or the discharge of water.
2. Prostenon. Apply in the initial stage, when the neck does not yet miss 2 fingers. The drug causes coordinated contractions without disturbing blood circulation in the "fetus-placenta" system.
3. Enzaprost (dinoprost). The drug is used in the phase of active disclosure, when the lumen of the cervical canal reaches 5 cm or more. The drug actively stimulates contractions of the uterine myometrium. At the same time, there is an increase in blood pressure, thickening of the blood. This medication is not used in the presence of preeclampsia, disruption of the blood coagulation system. Enter drip, dissolving in saline.

Cesarean section with weak labor activity

In the absence of the effect of the drug therapy performed, the deterioration of the fetus, a caesarean section is prescribed for weak labor activity. Emergency surgical intervention requires highly qualified doctors, the availability of conditions. If weakness arose during the period of exile (ineffective attempts and contractions), obstetric forceps are often used. This device helps to extract the fetus out. Timely delivery benefits reduce the risk of complications.

The content of the article

Weak labor activity, which is one of the most frequent and severe complications of the contractile function of the uterus, entails a large number of pathological conditions of the mother and fetus. According to our data, out of 30,554 cases of childbirth in urban obstetric institutions, the weakness of labor activity occurred in 2253 women in labor, which is 7.37%. The proportion of primiparas is 84%, multiparous - 16% (second births - 11.4%, third - 2%, fourth and more - 0.6%).
Clinicians distinguish two main forms of violations of the contractile function of the uterus during childbirth: weakness of labor activity and excessively violent labor activity. Moreover, in terms of the frequency of occurrence and the number of violations of the state of the mother and fetus, the weakness of labor activity is many times greater than the violent labor activity, which usually occurs in multiparous women.
There are primary weakness of contractions, secondary weakness of contractions and attempts, convulsive and segmental contractions. Excessively violent labor activity, in which the duration of labor with a full-term fetus is 3-4 hours, is called rapid labor.
The primary weakness of labor activity is manifested by contractions of weak strength, a violation of their rhythm and duration from the very beginning of their appearance and over a longer period of time. For secondary weakness of labor activity, the appearance of the same changes in uterine contraction at the end of the first or second stage of labor is characteristic. A variety of weakness of labor activity are convulsive and segmental contractions. The convulsive nature is manifested by prolonged, for more than 1.5-2 minutes, contraction of the uterus. During segmental contractions, not the entire uterus contracts, but its individual segments. Such contractions of individual segments of the uterus occur almost continuously, and their effect is negligible or extremely small.
The weakness of labor activity in a significant number of women in labor is preceded by a pathology of the condition of the membranes of the amniotic sac. 30.7% of women in labor had premature and 29.8% early discharge of water. There is a belief that the weakness of labor and the failure of the membranes of the fetal bladder in 60.5% of women in this group have the same cause.
We do not consider the untimely discharge of water as a weakness of labor activity. Many women with this pathology of the membranes - their reduced strength - have normal spontaneous labor activity.
In 32.9% of women in labor, abortions were noted in the past (artificial - in 23.4%, spontaneous - in 9.5%). As is known, artificial termination of pregnancy can have an adverse effect on the development of subsequent pregnancy and childbirth due to violations of the hormonal function of the ovaries and placenta, as well as anatomical defects in the structure of the myometrium. Spontaneous abortion is a direct consequence of the above violations, both on the basis of induced abortion, and congenital or acquired ovarian failure. Term delivery in this group of pregnant women was noted in 82%, before 38 weeks - in 0.8% and at a term of 42 weeks and more - in 17.2%.
In protracted labor, regardless of their genesis, the frequency of the use of surgical methods of delivery increases significantly. In medical hospitals in Ukraine, covering urban obstetric institutions, as well as rural central and numbered hospitals, operative methods of delivery in 1971 were used in 29.15 cases per 1000 births. The most common operation is vacuum extraction of the fetus - 16.01 per 1000 births, followed by caesarean section - 8.2, obstetric forceps - 3.54, removal of the fetus by the leg - 1.5 and fruit-destroying operations - 1.3.
The weakness of labor and the pathological conditions of the mother and fetus that accompany it are the reason for the use of the operative methods of delivery described above (252 per 1000 births). Moreover, vacuum extraction was performed in 142 cases per 1000 births, caesarean section - in 15, obstetric forceps - in 38, skin-head forceps - in 28, fruit-destroying operations - in 15 and extraction of the fetus by the leg - in 14 per 1000 births.
The prolonged course of labor increases the possibility of developing postpartum infection, which is observed 6 times more often than during normal childbirth, provided that a complex of preventive antibiotic therapy is carried out.
Labor anomalies are one of the leading causes of perinatal morbidity and mortality.
Of the total number of women in labor with weakness of labor, 34.7% experience pathological blood loss (over 400 ml) during childbirth or the early postpartum period. This pathology is the leading cause of maternal mortality and greatly complicates the course of a birth infection. All this points to the great practical importance of this problem.

Causes of labor activity

Despite the huge flow of information on the treatment of labor weakness and attempts to explain the mechanism of development of this pathology, this problem remains the least studied among other major problems of modern obstetrics.
The use of empirically substantiated methods of treating this pathology, the development of which is based on various mechanisms of dysregulation of myometrial cell contraction, often leads to unsatisfactory results and new searches for more effective means.
After the discovery of the mediator function of acetylcholine as a mediator of the transmission of nerve excitation to the effector organ, this concept was used to explain the mechanism of the development and course of childbirth. A.P. Nikolaev showed that in the blood of women in labor, amniotic fluid and cerebrospinal fluid, the mediator of nervous excitation, acetylcholine, circulates in a free form. The author suggested that the latter has an effect on the excitation of muscle cells and stimulates contraction. The release of acetylcholine into the blood, according to the author, is a consequence of the occurrence of excitation in various parts of the autonomic nervous system and the cerebral cortex.
A.P. Nikolaev and a large number of his followers believed that an increase in blood cholinesterase activity is the cause of the destruction of acetylcholine freely circulating in the blood and the development of motor inertia of the uterus. In the experiment, it was shown that acetylcholine enhances the contraction of the uterine horns of sexually mature rabbits in vitro. However, the use of acetylcholine preparations for the treatment of weakness of labor activity in the clinic turned out to be ineffective. Subsequently, it was proved that acetylcholine circulating in the blood does not have a direct effect on the spontaneously excitable system of the uterus during childbirth. The mediator acetylcholine is synthesized in nerve cells, nerve fibers and synapses. Being in vesicles, it is protected from destruction. Cell contraction is accompanied by the release of acetylcholine from synaptic vesicles, which, getting into the intersynaptic gap, leads to a change in the ionic balance and potential on the membrane of the effector cells, followed by a functional response of the excitable object. The mediator acetylcholine undergoes instantaneous destruction after the onset of the effect. The cycle is repeated. The presence of a small number of nerve terminal apparatuses in the uterus identified by modern methods of investigation raises doubts about the existence of a similar mechanism of excitation to contraction of the muscle cells of this organ. If the nerve conductors in the myometrial strip are cut, the processes of self-excitation and the response to tonomomotor drugs do not disappear.
The attempt of many authors to consider the weakness of labor activity from the standpoint of dysfunction of the cerebral cortex and vegetative centers was not successful. Sufficiently convincing facts about the direct participation of the higher parts of the central nervous system in the trigger mechanism of childbirth have not been obtained. However, in ensuring optimal conditions for the course of the birth process in the whole organism, the coordination of vital functions is provided by central regulatory mechanisms, and their role is indisputable.
With the preparation of preparations of the posterior pituitary gland (pituithrin), and later oxytocin, their high specificity was found in relation not only to the enhancement of spontaneous uterine contractions in vitro and in vivo, but also to the excitation of contractions of the myometrium, which was in a state of functional rest.
In the experiment and the clinic, it was shown that the weakness of labor activity is a consequence of the high activity of blood oxytocinase, which destroys oxytocin. It has been established that with the simultaneous administration of pituitrin and estrogen in case of weakness of labor activity, the tonomotor effect of pituitrin increases. This gave reason to talk about the inhibitory effect of estrogen on oxytocypase. It unfortunately, so far no convincing data has been presented confirming the mechanism of development of the weakness of labor activity described above. Cholinesterase and blood oxytocinase may be important to reduce the level of compounds destroyed by them, however, they do not have a direct effect on the function of organs (uterus). The use of a cholinesterase inhibitor - prozerin - proved to be ineffective in the treatment of weakness of labor, despite the increase in the content of acetylcholine in the blood.
More than 40 years ago, it became known that the sex hormones estrogen and progesterone have different effects on the long-term activity of the uterus: the former enhance it, while the latter inhibit it. Their widespread practical use for the purpose of excitation and inhibition of uterine contractions has become possible only since the synthesis of these hormones. It was also found that the functional state of the uterus can be maintained for a long time after removal of the ovaries by introducing sex hormones in accordance with the menstrual cycle. With the onset of pregnancy and in the dynamics of its development, the sex hormones of the ovary (in the early period of pregnancy), and later the placenta, have a decisive influence on the normal development of the fetus and the processes that determine the function of the uterus and the reaction of the mother's body to pregnancy. Clinicians have proven that one of the main causes of miscarriage is hormonal insufficiency of the ovaries and placenta. Hormonal correction of these disorders (estrogens + progesterone) gave a positive effect in all cases of pregnancy pathology of this genesis, if the treatment was timely and sufficient. In the next 15-20 years, an intensive study of the mechanism of action on the genital organs (mainly on the uterus) of estrogens and progesterone began in the state outside of pregnancy and in the dynamics of pregnancy. Of particular interest to clinicians were studies of the mechanism of hormonal regulation of uterine function during pregnancy and childbirth. Summary data of a large number of studies in this direction are presented in the monograph Jung (1965). Estrogen hormones as substances stimulating the spontaneous excitability of the uterus began to be widely used in klipika, often in very large doses.
It has been experimentally proved that the most favorable course of biochemical reactions in the tissues of the uterus is observed if the dose of estrogen administered to stimulate the uterus is 300-400 IU / kg. Doses of estrogens that are several times higher than the physiological ones lead to disruption of energy metabolism and suppression of the excitability of the uterus to drugs with an oxytocic effect. At present, a large clinical material has been accumulated on the combined use of estrogen and oxytocin, indicating a sufficient effectiveness of the method in the primary weakness of labor.
Over the past decade, the attention of biologists and clinicians has been attracted by two new biologically active compounds - serotonin and a group of prostaglandins, which have a fairly high selective activity in terms of stimulating the motor function of the uterus. The practical use of these compounds in the clinic to stimulate and induce labor has shown their high efficiency.
It must be assumed that in order to ensure the normal contractile function of the uterus, in addition to oxytocin, other uterotonic motor compounds are also needed that accumulate in the uterus and blood of women in labor (serotonin, catecholampins, prostaglandin).

Causes of weakness of labor activity

The reasons for the weakness of labor activity are as follows.
1. Genetically determined inertia of the mechanisms for switching on the functional systems of myometrial cells, which ensure the excitability and mechanical activity of its structures.
2. Insufficiency of the hormonal function of the fetoplacental complex, which determines the inclusion of cellular structures of the myometrium in the functional activity of excitation and contraction.
3. Morphological inferiority of the organ, causing insufficiency of function and inadequacy of the reaction to the complex of hormonal stimulation of the fetoplacental complex.
4. Functional inertness of the nervous structures (brain, spinal centers, regional nerve nodes), providing optimal conditions for the function of the uterus at the time of childbirth and in the dynamics of their development.
5. Fatigue of the uterus due to a violation of the normal anatomical relationships of the fetus and the birth canal (narrowing of the pelvis, large fetus, anomalies in the insertion and position of the fetus, structural changes in the soft tissues of the birth canal).
A large number of other factors identified as possible causes of the development of weakness in labor are subordinate to the above main reasons for the development of defective contraction of the myometrium during childbirth. Let us consider in more detail the mechanism of development of the weakness of labor activity for certain groups of reasons.
We consider the birth act as an unconditioned reflex reaction of the body, which is fixed in the hereditary apparatus of the cellular structures of the uterus and other organs, providing optimal conditions for the development of the function of this organ and the physiological conditions for the life of the fetus. The inclusion of uterine muscle cells in contraction occurs as a result of a change in the direction of specific hormonal stimulation of the gene apparatus of cellular structures. The main hormone influencing the contraction of myometrial cells are estrogens, the content and activity of which by the time of delivery change significantly in the direction of creating effects for optimal excitability reactions and contraction of the myometrium. Optimal levels of circulating estrogens in the blood and their fixation by receptor proteins of hormone-dependent cells stimulate the accumulation and activity of a number of other hormones and mediators (oxytoxin, serotope, prostaglandin Fua, catecholamines, and, apparently, other unexplored compounds with a specific action). The above biologically active compounds provide separate links in a complex self-regulating system of contraction of the muscle cells of the uterus, which is clinically manifested by childbirth. The birth act takes place at the maximum activity of the functions of many organs and functional systems (cardiovascular, excretory, metabolic, endocrine, etc.). The integration of the functions of all organs and systems of the body is carried out by the nervous structures of the brain, in which the dominant of childbirth is created, facilitating interhemispheric communications and subordination of the functions of the whole organism, ensuring the physiological course of the birth act.
If by the time the period of fetal development ends, the regulatory system of myometrial cells, which affects their excitability and contraction, does not respond to impulses emanating from the placenta and fetus, labor will not occur. The progression of pregnancy will continue until conditions arise for the inclusion of these functions of myometrial cells.
In some cases, the system of excitation and contraction of myometrial cells can be activated by neuropsychic shocks, acute infection, pain shock, vibration. It must be assumed that the excessively strong stimuli described above affect the mechanisms regulating cell function through the same humoral systems that are responsible for the mechanism of excitation and contraction during the physiological course of pregnancy. Confirmation of the correctness of the above statement about the genetic nature of the primary weakness of labor is also the fact that this pathology occurs mainly in primiparous women. The first childbirth is a kind of training for the mechanism of regulation of excitation and contraction of myometrial cells; with repeated births, this pathology is observed less frequently. The use of progesterone to block the contraction of the myometrium at various stages of the development of pregnancy enhances the processes of inhibition of the mechanisms of regulation of the tonomomotor function of cells by the time the uterine development of the fetus ends. We strive for such pregnant women to carry out prenatal preparation in order to prevent labor weakness, which in most of them removes the inertness of the mechanisms for switching on the topomotor regulation of the myometrium.
In women with ovarian dysfunction, especially with dysmenorrhea and menometrorrhagia, when pregnancy occurs, we observe high excitability and contractile function of the uterus in the early and late stages of pregnancy or tonomotor inertness in childbirth.
There is reason to believe that the violation (inhibition) of the regulation of the tonomomotor function of the muscle cells of the uterus can be caused both before and during pregnancy by other non-hormonal factors that are difficult to take into account and prevent.
Along with the cause of labor weakness described above, the latter may occur as a result of hormonal, mainly estrogenic, insufficiency of the fetoplacental complex. Our experimental and clinical studies have shown that estrogens are the main hormone that creates optimal conditions for the excitability of myometrium cell membranes and causes a cell response to substances that change the contractile properties of actomyosin. Until recently, it was believed that the leading role in the manifestation of the contractile function of myometrial cells belongs to oxytocin, although the mechanism of this action remains undiscovered. There are now many studies on the important role of serotonin and prostaglandin (F2a) in myometrial cell contraction. Under certain conditions, catecholamines (mainly adrenaline) have a pronounced tonomotor effect on the muscle cells of the uterus. The question arises, which of the above biologically active compounds is primarily responsible for uterine contractions during childbirth? We believe that the uterus, given its biological role in maintaining the life of the species, should have a duplicate system of specific contraction stimulators that compensate, and sometimes act as independent factors in the absence of the main one. The regulation of uterine contraction during childbirth includes two mutually determined dynamic processes: spontaneous excitability and contraction of muscle cells and energy metabolism, which provides the necessary levels of mechanical activity of the myometrium. A large number of biologically active compounds take part in the regulation of the first and second links of the uterus function, the effective action of which on the effector organ - the uterus - is possible only if there are optimal levels of fetoplacental hormones.
Clinical and experimental studies conducted by us and other authors (Jung, 1965) give reason to believe that compounds that affect the change in excitability and contractile properties of myometrial cells potentiate each other's action, and if one of them is insufficient, they can provide long-term time physiological parameters of uterine function.
When the contractile function of the uterus is weakened during childbirth, due to insufficient levels of circulating oxytocin or a violation of its use by myometrial cells, it is possible to completely restore uterine contraction by administering serotonin and calcium after pre-saturation of the mother's body with estrogens. Our investigations have shown that by successively introducing estrogens, serotonin and calcium, it is possible to overcome the motor inertia of the uterus and induce labor activity at various stages of pregnancy. The complex of biologically active compounds - estrogens, serotonin, calcium - ensures the restoration of the physiological course of the main links of the contractile function of the uterus in case of their violation and is the basis for initiating labor pains at various stages of pregnancy. Let us consider some of the mechanisms of these influences on the myometrium.
Serotonin (5-hydroxytryptamine, 5-HT) belongs to a group of broad-spectrum substances. However, it affects the smooth muscles in a strictly specific way. It has been established that the uterus has the ability to accumulate serotonin in large quantities (N. S. Baksheev, 1970; Fahim, 1965). Parenteral administration of labeled amine is accompanied by its accumulation in the subcellular fractions of the muscle cells of the uterus, where it is protected from destruction and can be stored for a long time (Kohren, 1965). With the introduction of 5-HT into the uterine lumen, active hyperemia, tissue edema, and stimulation of mitosis of muscle cells occur, similar to the action of estrogens (Spaziani, 1963). It has been established that there is a close relationship between serotonin and neuro-endocrine regulation carried out by the hypothalamic-pituitary system, and the amine itself is, apparently, a neurohormone with an autonomous, not yet fully disclosed mechanism of action. It has been shown that 5-HT relieves fatigue of muscle cells and restores their normal function (MM Gromakovskaya, 1967).
Studying the content of serotonin in some biological media and tissues of pregnant women, we found that during pregnancy, the concentration of 5-HT in the blood and uterine tissue increases, reaching the highest values ​​in childbirth.
In order to reveal the essence of the established relationship between the function of serotonin and calcium, N. S. Baksheev rt M. D. Kursky studied the effect of amine on the distribution of Ca45 + + in the uterine tissue and its subcellular fractions. The isotope was administered to animals (rabbits) intravenously.
Under the influence of 5-HT, the accumulation of Ca45 in the uterine muscle increases by 3.8 times, however, the degree of accumulation in each subcellular fraction is different. The most rapid and maximum accumulation of Ca45 occurs in mitochondria (at the 15th minute); this level is maintained for 180 mi p. in other fractions, the intensity of Ca45 accumulation decreases after 30 and 60 minutes. These studies have established that 5-IIT is responsible for the accumulation and metabolism of calcium in the muscle tissue of the uterus, both intravenously and intracisternally.
With the weakness of labor activity in the blood, uterine muscle and amniotic medium, the content of 5-HT is significantly reduced and the loss of calcium by uterine tissues increases. We believe that the biochemical system - fetoplacental hormones, serotonin, calcium - is responsible for providing physiological indicators of the contractile function of the uterus.
If serotonin is applied to a uterine strip that does not have spontaneous electrical activity, then in most cases spontaneous peak potentials appear after the depolarizing current is turned off, which indicates a significant change in the function of cytoplasmic membranes and contractile proteins under the action of amine.
In the absence of calcium ions in the medium, there is a shift in the membrane potential towards depolarization and a rapid loss of spontaneous electrical and mechanical activity, inhibition of excitability and an increase in the permeability of the protoplasmic membranes of smooth muscle cells of the uterus for other ions, that is, there is a complete disorganization of cell functions.
The addition of serotonin to a calcium-free solution does not affect the electrical activity and excitability of muscle cells.
If a muscle strip is preliminarily treated with serotonin in Krebs solution and placed in a calcium-free medium, the membrane potential value shifts towards depolarization, but the resistance of cytoplasmic membranes does not decrease, as is the case with the action of one calcium-free solution already in the 1st minute, but remains in within 4-5 minutes. After 5-8 minutes, the magnitude of electrotonic potentials slowly decreases and excitability decreases. Based on these studies, it can be assumed that 5-HT promotes an increase in the accumulation of calcium ions in the muscle cells of pregnant animals and ensures its economical consumption in a calcium-free medium for a long time.
The contraction of the muscle cells of the uterus during childbirth is associated with significant energy costs, the nature of which during pregnancy and childbirth is different. We have found that in the dynamics of pregnancy in the uterus, biochemical and morphological restructuring of the myometrium occurs, which provides the necessary level of motor function of the uterus during childbirth. The main role in these processes belongs to the hormones of the fetoplacental complex. To prove the role of estrogenic hormones, serotonin and calcium in these processes, we conducted experimental studies. If estrogen is administered to rabbits at the end of pregnancy (300 IU / kg for 3 days), an increase in the content of high-energy phosphates (LTP, CP), a decrease in glycogen and lactate , which indicates an increase in oxidative processes in the myometrium as a necessary phase for the manifestation of the contractile function of muscle cells.
With the introduction of the same doses of estrogens to non-pregnant rabbits, the amount of actomyosin increases 3 times (from 4.12 to 12.07%), and sarcoplasmic proteins containing enzyme groups, from 35 to 56.3%. The amount of proteins of the tonic fraction (fraction T) decreases by 50% and stromin proteins by 45%.
Significant changes were found in the myometrium of pregnant women in comparison with the state outside of pregnancy.
The content of contractile fraction proteins increases by 53% by the end of pregnancy, accounting for 40% of all myofibril proteins. The amount of sarcoplasmic proteins increases and the content of stromal proteins decreases.
Our studies show that serotonin and calcium administered separately and together (without estrogens) slightly change the fractional composition of proteins. With the introduction of these biologically active substances with estrogens, the accumulation of the optimal level of sarcoplasmic and contractile proteins occurs, and the content of adenyl nucleotides changes, the composition of which approaches that in the pregnant and giving birth uterus.
The system of adenyl nucleotides is the main system of the cell, which determines its energy costs.
We have already noted above that estradiol, serotonin and calcium, administered in a certain sequence, can restore the contractile function of the uterus weakened during childbirth. Normalization of contraction is possible with the restoration of oxidative metabolism.
Energy for muscle contraction of the uterus and other muscular organs is formed in the process of oxidative phosphorylation of carbohydrates (maximum energy output - with economical consumption of the substrate) and anaerobic decomposition of carbohydrates (minimum energy output with wasteful consumption of carbohydrates). During normal labor, the energy of uterine contraction is generated mainly in the cycle of oxidative phosphorylation, with the maximum use of oxygen. If labor is not completed within 16-17 hours, oxidative phosphorylation decreases, which can be determined by the use of oxygen by the uterine muscle obtained by caesarean section or by experimental fatigue of the uterine horn of animals. With a duration of labor of 18-24 hours, oxygen consumption by the uterine muscle decreases by 7%, 29-36 hours - by 17.2%, 99-121 hours - by 39.5%. The absorption of oxygen and the binding of inorganic phosphate in biological objects are in equimolar ratios.
This process is called coupled oxidative phosphorylation. The measure of oxidative phosphorylation is the P/O ratio (the ratio of esterified inorganic phosphate to absorbed oxygen). In normal childbirth, P/O pancake to the maximum and is 2.3. With a duration of labor of 99-121 hours, this indicator decreases by more than 2 times and is 1.1.
The transition of energy formation to the uneconomical path of glycolytic metabolism of carbohydrates is accompanied by the accumulation of excess products of interstitial metabolism (lactic, pyruvic acids).
The energy metabolism of fats is also disturbed, fatty acids and other oxidized compounds accumulate, depleting the tissue and blood buffer system. The consequence of this is metabolic acidosis and even more disruption of the homeostasis of tissues and fluids.
One of the reasons for the weakness of labor activity may be the morphological inferiority of the uterus due to trauma (abortion, surgical benefits in childbirth) and inflammatory processes. The resulting structural changes in the uterus significantly reduce the sensitivity of the mechanisms of regulation of the processes of biochemical and biophysical restructuring of all structures of the myometrium during pregnancy and childbirth. In these cases, even with a normal complex of humoral stimulants of the fetoplacental complex, there are no changes in the muscle cells necessary for the unleashing and normal course of childbirth. To this group of causes, we include overstretching of the muscles of the uterus (multiple pregnancies, polyhydramnios, large fetuses), in which there is often a weakness in labor activity.
Violation of the coordination of the functions of organs and functional systems of the body of pregnant women in the direction of creating optimal conditions for the development of the fetus and organs that ensure its vital activity and birth (placenta, uterus, amniotic medium) can weaken the contraction of the myometrium. These functions are combined by the central nervous system, the disorganization of which function can, in some cases, have a negative impact on the birth act.
To the last group of causes, we include fatigue of the uterus due to significant resistance to the advancement of the fetus from the side of the bone ring of the pelvis or soft tissues of the birth canal. The process of fatigue occurs during various periods of normal labor activity. Our clinical studies have shown that 16-18 hours after the onset of normal labor activity, paroxysms of oxidative phosphorylation occur in the myometrium, indicating a decrease in the use of oxygen in bioenergetic processes and the accumulation of acids and compounds close to them (lactic, pyroviogradic, butyric acids, etc.) that change the pH of tissues and blood. If labor activity cannot be turned off with the help of medications, not only biochemical, but also morphological changes in the muscle cells of the uterus may develop in the future, followed by persistent motor inertia of the organ. The muscle of the uterus in a state of fatigue loses the ability to fix serotonin, catecholamines, calcium. The synthesis of ATP and ADP is disrupted, glycogen stores are rapidly decreasing. With this pathology, it is necessary to prescribe medication rest (sleep) for 6-8 hours. If necessary, labor is stimulated according to the method described below.

Clinical forms of weakness of labor activity and methods of its treatment

The primary weakness of labor activity is manifested by weak and short contractions, which are accompanied by the opening of the cervix and the movement of the presenting part of the fetus into the underlying plane of the small pelvis. The displacement of the presenting part should occur no later than 4-5 hours from the onset of normal labor. With weakness of labor activity, the presenting part of the fetus can be in the same plane for 8-12 hours or more, which increases the swelling of the tissues of the birth canal and the presenting part. The first birth lasts an average of 16-18 hours, and repeated - 12-14 hours. If we take into account that the smoothing of the cervix in primiparas occurs on average within 4-6 hours, then the difference in the rate of opening of the cervix in primiparas and multiparas can be consider insignificant. For the full opening of the cervix, 10-12 hours of good labor activity are needed. The number of contractions from the beginning of childbirth to their end is 120-150 for most parturient women. Weak contraction of the uterus can occur due to the normal tone of muscle cells, as well as in the case of hyper- or hypotonicity. Hyper- and hypotonicity of the myometrium during childbirth can significantly reduce the effectiveness of each contraction. When establishing a diagnosis of the nature of the weakness of labor activity, it is necessary to strive to determine the tone of the body of the uterus, the state of which can be influenced to some extent by medications.
One of the varieties of weakness of labor activity is the segmental nature of contractions, which indicates the pathology of the spread of the contraction wave.
With the normal development of the contraction, contraction of the muscles of the uterine body occurs in one of the foci (usually in the area of ​​​​the uterine horn) and spreads down at a speed of about 10 m per 1 s. Due to a number of circumstances, the focus of excitation does not extend to the muscle cells of the entire body of the uterus, but covers only part of it. At short intervals after the contraction of one zone of the uterus, a second, and sometimes a third focus of excitation occurs. Such contractions, if determined on the basis of a zonal change in the state of the myometrium, can last 1-1.5 and even 2 minutes in the absence of progress in childbirth. Discoordinated labor activity increases the energy consumption of the uterus up to its significant depletion with an extremely low effect of childbirth.
One of the forms of labor pathology is the simultaneous contraction of the muscles of the body, cervix and lower segment of the uterus. The contractions of the muscles of the uterus and the lower segment largely offset the effect of the contraction of the body of the uterus, as a result of which conditions are created for the fatigue of the working organ.
Treatment of weakness of labor activity should be preceded by the establishment of a possible cause of this condition. The primary weakness of contractions most often has genetically determined causes or depends on the insufficiency of the hormonal function of the fetoplacental complex. Often there may be a combination of these causes.
The excitability and contractile function of the muscle cells of the uterus are influenced by oxytocin, serotonin and their combined use with estrogens and calcium, as well as a still little studied compound from the group of prostaglandins - prostaglandin F2a.

Induction of labor with oxytocin

Oxytocin is a biologically active compound with a highly specific action that enhances the contractile function of myometrial cells. It should be noted that oxytocin does not affect the myometrium, which is devoid of the influence of estrogen hormones, which not only sensitize the membrane and contractile proteins of muscle cells, but also create conditions for ensuring energy balance in a working organ. The mechanism of action of oxytocin on muscle cells has not yet been fully elucidated, however, there are data indicating a change in the ionic structure of target cell membranes to the level of the release of spontaneous action potentials. It must be assumed that oxytocin affects the transport of calcium ions in the intracellular structures of myometrial cells, without which contraction is impossible. The method of treating weakness of labor with oxytocin is as follows. 10 units oxytocin is dissolved in 350-400 ml of 5% glucose solution and injected intravenously or subcutaneously, starting with 10-15 drops per 1 minute. If in the next 4-6 minutes the contractions do not become more frequent and do not intensify, the volume of the injected solution is increased to 25-35 drops, and then the rate of inflow of the solution is regulated depending on the activity of the contractions. It should be noted that the effect of stimulation of uterine contractions by oxytocin is directly dependent on the readiness of the myometrium to respond to this hormonal stimulus. The duration of the stimulation period is 2.5-3.5 hours.
To enhance the sensitization of the uterus to oxytocin and increase the release of its own (pituitary) oxytocin and prostaglandin into the blood, as well as the accumulation of serotonin and catecholamines in the uterus, estrogens are prescribed prior to oxytocin stimulation. Estrogen is administered in ether (0.5 ml of ether per 1 ml of an oil solution of estrogen) in the amount of 300-400 units/kg of the mother's weight. Normal labor activity occurs against the background of the highest concentrations of estrogen in the blood. The highest concentration of estrogen in the blood after the introduction of an essential oil solution is observed after 3-3.5 hours, one oil solution (without ether) - after 5-5.5 hours. Oxytocin is administered 3-3.5 hours after estrogen with ether or 5.5 hours from the start of estrogen administration without ether.
The effect of stimulating labor activity is enhanced if estrogens in ether are administered 2 times in 20,000 units. (1st time - 3.5 hours before the start of oxytocin administration, 2nd time - before the administration of oxytocin), as well as with simultaneous intravenous administration of calcium chloride or calcium gluconate (10% 10 ml). On the day and on the eve of the stimulation of labor, ascorbic acid is prescribed (preferably galascorbin 1 g 3 times a day), coamide, vitamins Bi, Bis and cocarboxylase.
If after the introduction of 10 od. oxytocin, a weak labor-stimulating effect was obtained, it is not advisable to continue stimulation with quinine, pachycarpine or prozerin, since these drugs are many times less effective than oxytocin.
If the reaction of the uterus to oxytocin was sufficiently well expressed only during the administration of the drug, after its completion it is necessary to continue stimulation with pachycarpine (3% solution of 2-3 ml in 2-3 hours) or quinine hydrochloride (0.05 g of 1 powder in 30 min 4-5 times a day). The total dose of quinine, exceeding 0.7-1 g, is toxic. We noted above that dimecoline relaxes the muscles of the cervix and accelerates the opening of the latter.
Before and during the stimulation of labor, the appointment of trioxazine (400 mg 2 times a day) is shown - a tranquilizer, which also has some relaxing effect on the tissues of the cervix. When the cervix is ​​rigid, to accelerate its opening, 64-128 units should be injected into its tissue. lidase dissolved in 50-75 ml of 0.25% novocaine. It is necessary to monitor the nutrition of the mother. Other measures (laxatives, hot enemas) with drugs such as oxytocin, serotonin, or prostaglandin F2a are ineffective.

Stimulation of labor by serotonin

Serotonin, like oxytocin, is also used after the administration of estrogens in essential oil and oil solutions. 30-40 mg of serotonin-creatine phosphate is dissolved in 350-400 ml of 5% glucose solution immediately before administration. The drug is administered intravenously starting with 10-12 drops per 1 minute. After 5 minutes from the start of administration, in the absence of individual hypersensitivity of the uterus and vascular system, you can increase the amount of the drug to 20-30 drops per 1 minute. It is necessary to monitor the tone of the uterus, as well as the strength and duration of its contraction. At the time of administration of serotonin, after 30 minutes and 1 hour 30 minutes from the start of administration, calcium gluconate or calcium chloride (10 ml each) is administered intravenously.
If, as a result of stimulation with oxytocin or serotonin, childbirth did not end, after 16-18 hours from the start of stimulation, drug sleep is prescribed for at least 6-7 hours. Labor should not be stimulated twice a day, since the energy reserves of the uterus and physical strength are depleted women in labor. After rest, the vast majority of women in labor develop good spontaneous labor activity. If necessary, the stimulation is repeated. In the absence of the effect of the action of oxytocin, serotonin is used. However, often the other drug is ineffective.

Induction of labor

Premature discharge of water is an indication for the initiation of labor not earlier than 4-6 hours from the onset of rupture of the fetal bladder. During this time, some pregnant women spontaneously develop labor activity, which does not require medical correction in the future. If there are no contractions by the time indicated above, it is necessary to start initiating labor. To excite uterine contractions, we, just as with stimulation, first administer estrogens, believing that the pathology of the structure of the fetal bladder depends on the estrogen deficiency of the fetoplacental complex. Estrogens increase the excitability of the muscle cells of the uterus, increase the release of oxytocin by the pituitary gland and release from the uterus, and possibly from the placenta, prostaglandin F2 "" increase the accumulation in the uterus of serotonin, a progesterone antagonist, as well as the accumulation and synthesis of catecholamines. Estrogens and serotonin reduce the level and activity of progesterone, as a result of which its inhibitory effect on adrenergic parauterine and intrauterine nerve structures is reduced or completely removed. The adrenergic nerve approaching the uterus can form an efferent arc of the spinal reflex, as a result of which uterine contractions begin to be stimulated further by stretching (opening) of the neck. Adrenergic innervation increases the sensitivity of the myometrium to oxytocin.
Labor induction will be effective if the oxytocin test is positive. It should be noted that with a positive oxytocin test, the effectiveness of excitation of labor by serotonin significantly increases. The essence of the test is as follows.
Take 1 unit. oxytocin and diluted in 100 ml of 5% glucose solution (1 ml of solution contains 0.01 units of oxytocin). 3-5 ml of oxytocin solution (0.03-0.05 units) is slowly injected into the vein of the elbow bend. The drug reaches its maximum concentration by the 40-45th second. The second test of the readiness of the uterus for childbirth is the degree of "maturity" of the cervix for childbirth. The preparation of the cervix for childbirth consists in its shortening, softening and compliance, as a result of which the canal smoothly passes into the lower segment of the uterus. There is a thinning of the lower edge of the vaginal part of the neck, and the neck itself is located in the region of the wire axis of the pelvis. Practice shows that the above anatomical changes in the cervix correspond to a high degree of excitability of the uterus with the introduction of oxytocin and other compounds similar in effect.
The rate of administration of oxytocin and serotonin to initiate contractions should be somewhat greater than when stimulating labor. After the initial test for 4-6 minutes, the number of drops can be increased by 5-10 every 5-6 minutes and further adjusted depending on the labor activity of the uterus. If no effect is observed with the introduction of 40-50 drops per 1 minute, the rate of administration of oxytocin should not be increased. The same is true for serotonin. It should be borne in mind that there are few pregnant women with premature discharge of water and torpid inertia of the uterus. Their cervix, despite being prepared with estrogens, remains dense for several days, the tone of the uterus is low in the complete absence of spontaneous excitability and reaction to mechanical stimuli. The threat of endometritis, and sometimes the onset of endometritis, are the basis for the use of oxytocin or serotonin to induce labor. However, the full effect is missing. In this category of women, even with the simultaneous introduction of the metreirinter (in the absence of contraindications to its use), there are also no positive results, therefore, one has to resort to long-term mechanical expansion of the cervix with dilators, and then with fingers. Usually it is possible to expand the cervix by 3-5 cm in one go. After mechanical stretching of the cervix and application of skin-head forceps (with contraindications to metreyris), another round of labor induction is carried out. It is not uncommon to induce contractions that can later be stimulated by serotonin after oxytocin is administered, or vice versa. We have repeatedly been led to observe such inertia of the uterus that only with the help of mechanical methods it was possible to expand the cervix and remove the fetus.

Initiation of labor activity for medical reasons and in the event of a prolonged pregnancy

It is often very difficult to overcome the inertia of the uterus of pregnant women, especially when the pregnancy is overdue, and this requires a certain amount of time. Labor induction begins with an increase in the excitability of the uterus, which is achieved by the introduction of estrogens at 20,000-30,000 units. daily (estradiol dipropionate) in an oil solution, galascorbin 1 g 3 times a day and 10 mg serotonin intramuscularly 5 hours after hormone administration. Simultaneously with serotonin, calcium gluconate or calcium chloride is administered intravenously, 10 ml of a 10% solution. The period of prenatal preparation lasts 3-5 days, and sometimes longer. It is necessary to monitor the state of excitability of the uterus daily. In some pregnant women, after 2-3 days, arrhythmic contractions appear with a sufficiently high excitability of the organ. With a positive oxytocin test, labor induction with oxytocin or serotonin should be carried out according to the above scheme. If the contractions weaken after stopping the administration of the drug, oxytocin can be injected subcutaneously (2 units every 1.5-2 hours) or intramuscularly - 10 mg of serotonin every 2-3 hours. Pachycarpine and quinine should not be prescribed in the absence of contractions. B vitamins and coamide are prescribed during the entire period of labor induction. If after the first treatment the effect is not obtained, the second should be carried out no earlier than in 1-2 days, continuing the appointment of estrogens and other drugs according to the above scheme. Our many years of experience in the use of the above method of labor induction testifies to its consistently high efficiency and the least number of complications in the fetus.
In the absence of oxytocin and serotonin, pituitrin (10 units) can be used, but it should be administered only subcutaneously, since collapse may occur with intravenous administration. With late toxicosis, serotonin and pituitrin should not be administered.
With secondary weakness of labor activity, when labor has entered the second period, and uterine fatigue and general physical fatigue are increasing, you can use a 1% solution of sigetin, which is administered in an amount of 2-4 ml (preferably in 20 ml of 40% glucose), and then drip introduce oxytocin or serotonin and calcium gluconate. If necessary, resort to operative delivery. If secondary weakness develops at the end of the first period of labor, one of the schemes described above can be applied.
When prescribing medical sleep (rest) to a woman in labor, we use the following combinations of medications: I - trioxazine - 600 mg, etaminal sodium - 200 mg, promedol 2% - 1 ml, no-shpa - 2 ml, pipolfen - 50 mg; II - viadril G - 50 mg intravenously, trioxazine - 600 mg, sodium etaminal - 100 mg, no-shpa - 2 ml, pipolfen - 50 mg; III - sodium hydroxybutyrate (GHB) 20% - 20 ml intravenously, no-shpa - 2 ml, pipolfen - 50 mg. Etaminal sodium can be replaced with noxiron. Discoordinated contractions decrease under the influence of no-shpa, atropine, palerol, aprofen (the latter relaxes the muscles of the cervix).
The weakness of labor almost always worsens the condition of the fetus (acidosis, hypoxia, cerebral edema). Therefore, it is necessary to carry out effective prevention of fetal asphyxia simultaneously with the stimulation of labor. Weakness of labor is a very common diagnosis today. Weakness of tribal forces is more common in primiparous women. Weak labor activity can be primary and secondary. Contractions can be of satisfactory strength, but rare, or frequent, but weak and short. Persistent weak labor activity may be the reason for the appointment of a caesarean section. Despite the fact that weak labor activity refers to complications that occur directly during childbirth, you can try to prevent its development even during pregnancy. Weak labor activity leads to a protracted labor process, causes fatigue in the mother and hypoxia in the child, overwork of the woman in labor, labor bleeding, infection of the birth canal.

In the first place of the anomalies of labor activity is the weakness of labor activity. Weak labor activity is a pathology of the labor process, which consists in weak, short and fading contractions. With the weakness of labor, contractions are weak, rare, short, and the rate of opening of the uterine os is less than 1 cm per hour (and for multiparous less than 1.5-2 cm per hour). Smoothing of the cervix and its opening occurs at a slow pace and therefore remedial measures will be required as soon as the diagnosis of weakness of labor activity is established. At present, the scheme of labor-stimulating therapy according to Stein-Kurdinovsky with the use of oral quinine and intramuscular administration of oxytocin is not recommended, which is due to the fact that the effectiveness of oral administration of quinine followed by the administration of oxytocin is very small and poorly regulated.

Therefore, at present, only the scheme of intravenous administration of oxytocin or prostaglandins with a possible combination is used (enzoprost or prostenon is administered for 2 hours, then an ampoule of oxytocin is added and uterotonics are administered within 3-4 hours with an assessment of labor-stimulating therapy, therefore it is necessary to treat weakness of labor activity in a timely manner. The diagnosis of weak contractions should be made no later than 3 hours after the onset of contractions and treatment should begin immediately with active drugs.

NB!labor induction- These are therapeutic measures in the absence of contractions.
Rodostimulating therapy- in the presence of weak contractions.

If you follow medical statistics, then weak labor is a fairly common phenomenon - 10% of all births.

But is it really so? Indeed, in the average generic department, everything is put on stream. And there they don’t particularly listen to the inner feelings of women in labor. Doctors quite often, without special need, just to secure and speed up the process, resort to stimulation of labor activity, referring to its weakness.

The weakness of labor activity is characterized by the presence of contractions weak in strength, short in duration and rare in frequency. With such contractions, the opening of the cervix and the movement of the fetus through the birth canal is slow. It can be primary, secondary, and appear only in the period of exile.

Cyclic weakness of labor occurs in the risk group which consists of the following pregnant women:

1. elderly and young women

2. women with overstretching of the uterus (large fetus, multiple pregnancies, polyhydramnios).

3. Multiparous, multipregnant, numerous abortions with curettage, that is, in the presence of dystrophic and inflammatory changes in the myometrium.

4. In women with menstrual dysfunction and hormonal imbalance

5. hypertrichosis obesity

Cyclic weakness of labor activity develops in the group in which the uterus is unable to respond to normal impulses from the pacemaker. There may be a lack of impulses or a lack of receptors.

The diagnosis of weak labor activity is made on the basis of:

1. characteristics of contractions: weak, short

2. insufficient dynamics of cervical dilatation (normally 1 cm per hour) - 2-3 cm per hour.

3. To clarify the dynamics, external methods of determination and data from a vaginal examination are used.

4. The diagnosis must be made within 2-3 hours.

The weakness of labor activity leads to prolonged labor, complicated by premature or early discharge of amniotic fluid, leads to fetal hypoxia. Increased risk of purulent-septic complications. In the third stage of labor causes hypotonic bleeding.

Causes of weakness of labor activity

There are a number of reasons for weak labor activity:

• hormonal failure: the body of a woman giving birth is such a delicate and sensitive instrument that even a little stress - for example, a rude word - can cause labor to fail. Fear of the unknown process of childbirth for primiparas can also be the cause of weak labor activity. Also, the cause may be disorders of the endocrine system, menstrual irregularities, metabolic disorders;
• features of the physiology of the body: a narrow pelvis in a future mother or a flat bubble;
• pathological processes in the uterus: malformations, inflammation, excessive stretching;
• other reasons: polyhydramnios, large fetus or multiple pregnancy, obesity, post-term pregnancy.

We must also take into account the fact that even in one woman, the first and subsequent births can proceed in completely different ways. Weak labor activity can be encountered even at the birth of a third child. In such cases, the cause of weak labor activity can be constant overwork, lack of sleep.

Prevention of weak labor activity

One of the most important factors for successful childbirth is the psychological attitude of the expectant mother. It is best to attend childbirth preparation courses, where specialists will teach you how to behave during childbirth and help you positively tune in to difficult and important work - the birth of a new person.

Pre-induction of labor

If the family has already had cases of weak labor activity or there is reason to suspect that the birth will be protracted, you can take care of a safe delivery in advance.

Pre-stimulation can be started at home from 34-36 weeks of pregnancy. It is based on the principle - to do what could not be done in recent months: wash the floor on an incline, have sex, lift weighty objects, take hot baths.

You can also make tea with raspberry leaves and drink 2-3 cups a day. But in everything, of course, a measure is needed.

Stimulation of labor in the maternity hospital

Initially held non-drug stimulation- opening of the fetal bladder - amniotomy. This procedure is performed when the cervix is ​​dilated by 2 cm or more.

Very often, after opening the fetal bladder, labor activity intensifies. The mother is observed for several hours. If the amniotomy did not give the desired result, and the process did not accelerate, medical stimulation is used.

The most common method is drug stimulation uterine contractions with the help of uterotonics: oxytocin and prostaglandins. They are administered intravenously. At the same time, the condition of the fetus is monitored using cardiotocography.

To restore the forces of the woman in labor, drug sleep is used. It lasts about 2 hours. It is called with the help of analgesics, in consultation with the anesthesiologist. Sleep is used in very rare cases, when the benefits of using this method are much greater than the harm done to the fetus.

In some cases, when none of the methods does not help and the condition becomes threatening for the child or mother, an emergency caesarean section is performed.

The usual scenario of labor induction

Often, stimulation is simple and quick. If contractions are present and the disclosure is somehow, but going on, then the plot can unfold as follows: a dropper in the hand, a pill under the tongue and, on command, on the birth table.

The order is to push without pushing. A couple of "kind" words to the poor exhausted head of a woman in labor. And, in conclusion, - hefty aunts fall on their stomachs and simply squeeze a baby out of a woman. The pelvic bones crack, the child is born with a hematoma all over his face. Hooray, a man is born!

Most often, stimulation saves the health and even life of an infant, but sometimes it can also cause childhood disability.