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How to calculate what is the gestational age. Terms - obstetric and embryonic period

To understand what a gestational age of 1 week means, you need to figure out from what moment the countdown is being conducted.

1 obstetric week of pregnancy is the week that starts from the first day of the woman's last menstruation in the cycle when conception occurred. From this week, 40 weeks are counted and the date of birth of the baby is obtained. In fact, at this time the woman is not yet pregnant.

1 week from conception - as a rule, this is already the third obstetric week (it all depends on whether the woman ovulated earlier or later).

1 week from the delay of menstruation is already the fifth obstetric week. Usually, the first signs of pregnancy in expectant mothers appear during this period. Let's talk about them.

First signs of pregnancy at 1 week

All the variety of signs that tell a woman that she is pregnant is purely individual. Someone feels the whole "bouquet", and someone does not even know about the role of the future mother.

However, most often the main signs of pregnancy at 1 week are:

- delayed menstruation (but let's not forget about women with a bicornuate uterus - they can have periods during the period of bearing a child);

- nausea or even vomiting as an early manifestation of toxicosis;

- feeling of weakness, lethargy and drowsiness;

- a sharp exacerbation of susceptibility to pungent odors (you may not like everything: from your husband's toilet water, which you loved so much before, to the smell of meatballs);

- a change in taste preferences (drawn to a particular product or, conversely, an aversion to a certain dish appeared);

- unclear slightly pulling pains in the lower abdomen, headaches or pulling pains in the lower back;

- breast enlargement or pain in it (more in the article breast changes during pregnancy);

- emotional instability (sudden mood swings);

- a pregnancy test (it does not always show a true result in the first week, because the level of the pregnancy hormone - hCG - in a woman may not reach the required minimum in order for the test to give a positive result).

Development of pregnancy at 1 week

An embryo grows inside the mother. It is still extremely small - smaller than the size of a pinhead. In fact, this is just a group of cells, however, they reproduce and grow unusually quickly.

From each of the parents, the baby has already received 23 chromosomes. So now he's the perfect combination of mommy and daddy's chromosomes.

At the time of fertilization, the sex of the baby was determined. This was influenced by the father's sperm, which fertilized the egg. A Y-chromosome carrier will bring you a wonderful boy, and an X-chromosome carrier will bring you a wonderful girl.

You most likely do not notice any changes in yourself yet. Many at this stage are not aware of their pregnancy. Unless they assume on some grounds.

It happens that during the implantation of an already fertilized cell, a woman may notice a slight bleeding. Just a drop. But this is optional.

If you are planning your pregnancy or not planning, but the first signs have already appeared, you need to think not only about your health, but also about the health and safety of your unborn baby. Every expectant mother needs:

1. Refuse to drink alcohol. It is important to completely eliminate smoking: both passive and active. Breathe in fresh air as much as possible.

2. Take any medications with caution. For any treatment, consult your doctor. Most drugs, even the most harmless, in the first weeks of pregnancy can cause irreparable harm to the baby.

3. Take folic acid. This is the main vitamin for those who are just planning a child and already pregnant women. It protects the fetus from a huge number of birth defects. In addition to tablets, it is found in such products: spinach, asparagus, carrots, egg yolk, apricots, pumpkin.

4. It is advisable to take a daily multivitamin preparation designed specifically for pregnant women. Also eat fruits and vegetables at every meal.

5. Avoid physical and mental overstrain, as well as stress.

From what day is pregnancy counted

Sat, 08/28/2010 - 17:42 - Valentine

ovulation

Two strips on the test are not always a guarantee of pregnancy, but in 95% of cases they are considered news of the onset of conception. At the moment when a woman sees the cherished lines of red, she is overcome by mixed feelings, and the main thing at this time is to firmly realize: now you are responsible for a small life that will warm under your heart for nine months.

How to give birth to a healthy child?

The first thing a future mother will have to face is regular examinations. Traditionally, after an appointment with a gynecologist, tests are taken, and then doctors of various practices are bypassed to assess the general health of a pregnant woman. If all is well, then the lady is assigned regular visits (usually every 2 weeks) to the obstetrician-gynecologist, who will monitor the development of the baby in the womb.

Pregnant women are capricious and irritable. It is difficult for them to get out of bed early in the morning, because they constantly get sleepy, so many representatives of the weaker sex believe that mandatory attendance can be skipped. Such an opinion is a great delusion, since only a doctor can determine adverse changes in the condition of a pregnant woman or a fetus that the woman herself will not notice.

How does it work? The fact is that it is difficult to call pregnancy an easy time, and every lady who carries a baby under her heart constantly experiences certain discomfort. Both slight sipping in the lower abdomen and moderate soreness in the lower back are considered normal, but each person has his own sensitivity threshold, therefore, when one woman seems suspicious that her stomach has been pulled too much, the other may not notice changes in her condition.

In addition to timely visits to the doctor, a pregnant woman needs to monitor her health on her own. Usually, experts advise to measure pressure at home, since in a woman in position it is often unstable.

It is very important to observe the daily regimen and a special diet, the best option for which for each expectant mother is selected by her leading obstetrician-gynecologist.

Alcoholic drinks and narcotic drugs are strictly prohibited during childbearing, since their use is the most common cause of intrauterine malformations in a baby.

Causes of miscarriage

A miscarriage can be called the scourge of the modern world. Despite the high-tech equipment of medical equipment and the high qualification of doctors, compared to the last century, the percentage of spontaneous miscarriages has increased several times in our time, and this is due not only to the environment, but also to the attitude of young women to pregnancy.

Modern life dictates that we are constantly on the move, and the expectant mother simply needs physical and emotional peace. That is why one of the first causes of spontaneous miscarriage is non-observance of the proper daily routine and negligence of expectant mothers in relation to their condition.
Another reason for miscarriage is sexually transmitted diseases that were transferred before conception, which are usually accompanied by an inflammatory process in the reproductive system. A girl, even at a young age, needs to think about the rules for protecting herself from various sexually transmitted diseases, because the state of her female health can affect both the development of a future pregnancy and the development of a child in the womb.

It often happens that a prevented miscarriage does not protect the fetus from defects and the child is born handicapped.

How to calculate the date of conception of a child?

Pregnancy in the life of every woman is not only a wonderful, but also a crucial period that will require a lot of strength, attention and patience from her. Therefore, it is very important for a girl to know from which day to consider pregnancy in order to be ready for the changes that will occur in her body as early as possible.

Doctors consider the beginning of pregnancy the first day of the last menstruation, although the fertilization of a female egg usually occurs on the days of ovulation. With a standard menstrual cycle of 28 days, ovulation usually occurs on the 14th day of the cycle, and it is at this time that conception most often occurs.

The medical gestational age, starting from the first day of the last period, is calculated in this way to avoid confusion associated with the use of different reference dates. If a woman knows exactly the day of conception, then she will not have a question from which day to consider pregnancy, but the doctor will still set a period of two weeks more - this will be the medical term of pregnancy.

The key to the health of the future baby is the strict observance of the rules established by the obstetrician-gynecologist. The responsibility placed on a woman during pregnancy is quite large, but it cannot be compared with the happiness that a born child can bring to the life of any family.

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What is the most common question asked by pregnant women? "What time frame are you on?" It turns out that answering it correctly is a whole science. Let's try to master it.

Terms - obstetric and embryonic period

When registering for pregnancy in the antenatal clinic, the doctor will determine and use obstetric term. Its countdown starts from the first day of the last menstruation, and the calculation is carried out in weeks. The average full-term pregnancy according to this calculation of terms lasts 40 weeks (280 days). Previously, such a period was considered in months - the well-known 9 months (actually 9 months and 7 days). Currently, the question "What month are you on?" can drive a pregnant woman into a stupor - she is much more willing to tell what her week is!

Interestingly, at determining the duration of pregnancy by menstruation in the first 2 weeks, there is no such period of pregnancy as such, because conception has not yet taken place.

Another way to calculate the term is by conception. It is also called embryonic period or true. Most often, it is difficult to say exactly when the conception occurred - the union of the egg and sperm - rather, we can talk about the known date of ovulation or proximity, as a result of which a new life was born. Such terms can be indicated in the ultrasound protocol or on the form of the results of the analysis for human chorionic gonadotropin (hCG). Clarify this point to avoid confusion and unnecessary worries.

Correction of the obstetric period for late and early ovulation

The obstetric term is calculated based on the "ideal" 28-day female cycle with ovulation on day 14. If it is known that ovulation occurred later or earlier, it would be logical to correct such a period. To do this, you need to determine the conditional start date of the "correct" menstruation - subtract 14 days from the known date of ovulation. From this day on, count the "legitimate" 40 weeks. Accordingly, real late ovulation pregnancy will be less than calculated simply from the date of the beginning of menstruation.

Determining the gestational age by ultrasound

A good help in determining and clarifying the timing of pregnancy is ultrasound diagnostics.

At the very beginning of pregnancy, when you may not even be sure about it yet, the fetal egg is measured with the help of an ultrasound study. Unfortunately, the average internal diameter (SID) of the fetal egg can tell about the gestational age very approximately, since possible fluctuations in terms for this parameter can be up to 1.5 weeks, both up and down.

When the embryo begins to be visualized in the fetal egg, the coccygeal-parietal size (KTR) is measured. This is the maximum distance from the head end (temechka) to the coccyx. Measurements are taken at the moment of maximum extension of the embryo. If you have an irregular cycle, or you are not sure when you ovulated, this size is the best way to determine your baby's fetal age. This indicator is used for determining gestational age with Ultrasound during the first trimester.

Table 1. Coccyx-parietal dimensions of the embryo/fetus in the first trimester of pregnancy

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by the first movement of the fetus;
by measuring the length of the uterus.

Only an experienced gynecologist can calculate a more accurate gestational age, but you can independently try to find out the gestational age online on the Internet on sites for pregnant women and then compare your results with the doctor's calculation.

The first way: by the date of ovulation. Recall that ovulation is a period of menstruation in which a mature egg becomes ready for fertilization. That is, this is the most optimal day for conception.

To determine ovulation, you can measure your basal temperature daily, you can buy special tests at a pharmacy, and some women can determine ovulation by how they feel: pain in the lower abdomen, abundant discharge from the vagina, increased libido.

According to statistics, ovulation in most women occurs in the middle of menstruation. If you have a menstrual cycle of 28 days, then ovulation will occur on the 14th day, if the cycle is 35 days, then on the 17-18th day. The gestational age at conception begins to count from the day of ovulation.

Second way:gestational age monthly . A fairly simple method, we discussed this method above, it is used by obstetricians in order to determine how long the pregnancy is. If a woman has an irregular menstrual cycle, this method cannot be considered reliable. The third way: by examining a gynecologist. It is much easier to calculate the gestational age by weeks in the early stages. If your pregnancy is before 4 weeks, an experienced gynecologist will be able to most accurately determine your due date, based on the size of the uterus. For example, at week 4, the size of the uterus will be the size of a chicken egg, on the 8th - with a goose.

Up to 8 weeks, the gynecologist can determine the gestational age with high accuracy, even up to one day.

After 12 weeks, this will be more difficult to do, due to the fact that all babies develop in different ways, and in women with the same period, the size of the uterus will be different. The fourth way: by ultrasound. To determine the gestational age using ultrasound, it is also important how many weeks the pregnancy has already lasted: up to the 12th week, it is possible to determine the period more accurately. Further, there may be failures.

At a later date, the error of an ultrasound specialist increases due to the fact that each baby develops individually: some children are larger, others are smaller.

Fifth method: according to the first stirring. It is believed that women who carry their first child under the heart feel movements at the 20th week, with the next birth - at the 18th week.

But, this method does not always give the correct result, since the expectant mother can confuse the movements with the "work" of the intestine. As you know, during pregnancy, a woman is characterized by increased gas formation.

Sixth method: by measuring the length of the uterus. This method can only be used by a gynecologist. The doctor measures the length of the uterus with a measuring tape. The gestational age of a woman will be equal to the length of the uterus.

For example, the length of the uterus turned out to be 25 cm, which means the pregnancy is 25 weeks. It is important to empty before measurements, otherwise there may be an error in the measurements.

Here we are with you and considered some methods of how to find out the gestational age. Once again, we repeat that it is very rare to determine the exact date of birth and gestational age.

The baby will be born when he is ready, regardless of our calculations. Good luck with your pregnancy timing. Take care of yourself and your future baby.

Gestational age

At your first visit to the antenatal clinic for pregnancy registration, the doctor's attention will be paid to such an issue as determining the gestational age. Knowing the gestational age, the doctor will be able to set the expected date of delivery, as well as monitor the course of pregnancy throughout its entire duration, conducting the necessary examinations on time and identifying possible problems if any indicators do not correspond to the current gestational age.

The determination of the gestational age is carried out more than once: throughout the entire pregnancy, its period can be specified several times. There are several ways to determine the gestational age. Some are based on the results of examinations, others are a specific methodology, using which a woman can calculate the gestational age on her own.

First of all, some information about the day the gestational age begins. The obstetric gestation period, the total duration of which is 40 weeks, is calculated not from the moment of conception, but from the first day of the last menstruation. With a regular menstrual cycle of 28 days, the probability of conception is highest on the 14th day after the start of menstruation. Thus, when pregnancy occurs, the gestational age at the date of conception will already be considered equal to two weeks.

Determining the gestational age by the date of the last menstrual period is used as the initial method for calculating the gestational age. However, this method may have significant errors in determining the exact gestational age, especially if the menstrual cycle is irregular or shorter or longer than 28 days. To clarify the gestational age, the following methods are also used: measuring the uterus, determining the level of hCG, conducting an ultrasound scan.

Measuring the length of the uterus will show how pregnant a woman is at any particular moment, with sufficient accuracy: the gestational age in weeks is approximately equal to the length of the uterus in centimeters. Measurements of the uterus are made every time you visit a gynecologist using a regular centimeter.

Carrying out an ultrasound examination (ultrasound) is one of the most accurate ways to determine the duration of pregnancy at an early stage. Calculate the gestational age based on the ultrasound readings, preferably up to 10-12 weeks of pregnancy, then the calculation will be very accurate. In the future, the use of ultrasound to determine the gestational age can give more and more errors. The fact is that it is possible to determine how long the pregnancy is with the help of ultrasound, based on data on the size of the fetus. Up to 10-12 weeks of pregnancy, this indicator is almost the same for everyone, and then the size of the fetus in different women at the same stage of pregnancy can already vary significantly.

You can also find out the gestational age by the level of the hormone human chorionic gonadotropin (hCG) in the blood of a pregnant woman; for each gestational age, their own hCG levels are set. However, a clear discrepancy between the level of hCG and the duration of pregnancy may indicate significant problems, such as miscarriage or ectopic pregnancy, which makes this study even more significant.

Previously, in order to determine the duration of pregnancy, data were used on when a woman began to feel the first movements of the child. It is believed that primiparous women begin to feel the baby's movements around the 20th week of pregnancy, second-born women around the 18th. However, all this is quite individual, and some may feel the movements of the baby a little earlier, others later, so determining the gestational age in this way is not currently carried out, since there are already other, modern methods for determining the gestational age, which give greater accuracy.

In general, to determine and clarify what gestational age is observed in a woman, several methods are used in combination, which makes it possible to make the determination of the gestational age as accurate as possible.

Every expectant mother wants and strives to ensure that the pregnancy proceeds without complications, and the baby is born strong and healthy. To do this, you need to correctly determine the date of conception and the timing of pregnancy.

It is very difficult to say with accuracy on which day the conception took place, even for gynecologists with a long work experience. But you can find out the approximate date. There are several ways to define it. Let's take a look at these methods and their pros and cons.

1. You can determine the term of conception by the date of the last menstruation. This method of calculation is suitable for women with a regular menstrual cycle. To do this, you need to count two weeks from the first day of the last menstruation. The method of this calculation is explained by the fact that conception can occur only after ovulation. For example, if your cycle lasts 26 days, then the period of ovulation will be between 11-15 days. With this method of calculation, an error of 1-2 weeks is allowed.

By the date of the last menstruation, you can find out the approximate date of birth. The following 2 methods are very popular and simple:
- 280 days are added to the date of the first day of the last menstruation. The received month and date will be the approximate date of the beginning of the birth process.
— Negel's formula. Subtract 3 months from the date of the most recent period and add 7 days.

2. If you forgot when your last period was or have an irregular cycle, an ultrasound will come to the rescue in this situation. At the initial stages of pregnancy (up to the 7th week), all embryos have the same rate and signs of development. It is an ultrasound examination in the early stages that will help to find out the most accurate date of conception. After 7-8 weeks, all children begin their individual development, therefore, the longer the gestation period, the more difficult it is to determine the date. The study of ultrasound provides not only the most accurate indicators of the term of conception, but also helps in identifying pathologies.

3. All women, suspecting that they are pregnant, immediately rush to the gynecologist for an examination. But, unfortunately, the doctor will be able to say a more accurate date of fertilization only at an early stage of pregnancy.
From the second trimester, doctors can determine the date of pregnancy by the length of the uterus. As you know, with each subsequent week of pregnancy, the uterus increases in size by 1 cm. Lying on a couch or gynecological chair, the doctor feels the uterus and determines its size using a centimeter.

There is also a special table by which you can find out the gestational age by the location of the uterus relative to the womb and navel.

- At 12 weeks, the uterus is located closer to the upper edge of the womb.
- At 14 weeks of gestation, the uterus is located below the womb at a distance of about two fingers.
- At week 16, the location of the bottom of the uterus is between the navel and the womb.
- At 20 weeks, the uterus descends below the navel.
- At 24 weeks, the uterus is located at the level of the navel.
- At 28 weeks, the bottom of the uterus is above the navel at a distance of two fingers.
- At 32 weeks, the length of the uterus reaches 27-30 cm and is located between the short part of the sternum (xiphoid process) and the navel.
- At 36 weeks, the uterus is located so that it supports the ribs.
- At 40 weeks, before the birth itself, the child changes its position and prepares for the exit, so the uterus takes a position between the navel and the xiphoid process.
Again, this method of determining the period has its own errors, since the body of each woman in a position has individual characteristics.

4. The exact gestational age can be determined by the calendar method. The calendar method includes the measurement of basal temperature over several cycles. The temperature should be measured every morning at the same time. The data is recorded in the form of a graph, according to which the day of conception is determined. This method also includes those cases when a woman has rare sexual intercourse and knows the date of the last intimacy.

5. You can determine the date of conception by passing an analysis of hCG. To analyze the level of chorionic gonadotropin, blood is taken from a vein. This method of calculation is inaccurate even at the initial time. This analysis is more carried out to identify pathologies in the fetus and to identify the pregnancy itself.

6. The gestational age is determined by the very first movement of the baby in the womb. Women who give birth for the first time should feel the first movement strictly at 20 weeks. And those giving birth for the second or third time feel the first stirring 2 weeks earlier, that is, at 18 weeks. This method of calculating the term is also not very accurate, since the course of pregnancy is a purely individual process. Many expectant mothers often confuse the first movement of the baby with the activity of the intestines. This is due to the fact that almost all pregnant women have increased gas production.

7. The approximate date of conception can be found by the size of the abdomen. With this method of determination, it is necessary to take into account the weight and physique of a woman. Measurement of the volume of the abdomen occurs with the help of a centimeter at the level of the navel.

The gynecologist can calculate the most accurate date by collecting the data of all the above indications. If the pregnancy is multiple, childbirth can begin 2-3 weeks earlier than the expected date.

True and obstetric terms of pregnancy

The true gestational age is calculated from the last release of the egg or the so-called ovulation, which occurs 2 weeks after menstruation. Let us remind you once again that it is possible to determine the exact time of ovulation only with a regular menstrual cycle. The obstetric period is calculated from the first day of the last menstruation.
The difference between these terms is that the true term is 2 weeks less than the gynecological one.
Every expectant mother should remember that plans for the birth of a long-awaited baby may not coincide with the calculations of even the most experienced gynecologist.

The pregnancy calculator allows you to calculate the exact due date and find out what week of pregnancy you are currently in, as well as the expected date of delivery. To calculate, select the date of the first day of your last period at the top of the calculator and click on the "Calculate" button. The calculator will then automatically display your current pregnancy week and expected due date.

For each week of pregnancy, two exact dates are displayed: the start day and the end day. The interval between them is exactly 7 days. You can scroll through the weeks of pregnancy using the arrows. The full list of weeks from 1st to 40th is at the very bottom of the calculator. By clicking on them, you can also scroll through the slider for the desired week. The trimester of pregnancy to which each week belongs is indicated by Roman numerals at the bottom (near the slider) and in the upper right corner of the cells (in the full list of weeks). Also, the trimesters are marked in pink, orange and blue, respectively. In general, the very concept of pregnancy trimesters is rather arbitrary and their boundaries are not clearly defined. We took as a basis the most common classification, in which the second trimester begins at the 14th week and ends at the 28th. Only your obstetrician-gynecologist can calculate trimesters more accurately after an ultrasound scan.

In the images you can see a rough illustration of the development of the baby inside the womb for each week. To the left of the images is a summary of the fetal growth for that week. For more complete and detailed information, you can find by clicking on the "More" link, which is located under each description.

Method for calculating the gestational age

The calculator calculates the so-called "obstetric" gestational age. It differs from the actual date by about two weeks. This calculation method is used in gynecology, because. it is very difficult to calculate the exact day of conception. Therefore, the calculation is based on the first day of the last menstruation, the date of which, as a rule, every woman remembers. 280 days or 40 weeks are added to this day. Thus, the first two weeks of the obstetric period you are not yet pregnant, because. ovulation has not yet occurred (based on an average menstrual cycle of 28 days). This method is not completely accurate because some women ovulate late or early. But, in general, for most expectant mothers, such a calculation turns out to be quite accurate.

In any case, we draw your attention to the fact that the pregnancy calculator allows you to calculate the term using the most general formula, which does not take into account the individual characteristics of your body. It cannot be used for self-diagnosis or any other medical purposes, since the results of its calculations are for informational purposes only. All precise calculations and any other manipulations should be done only by your attending physician.

What is the most common question asked by pregnant women? "What time frame are you on?" It turns out that answering it correctly is a whole science. Let's try to master it.

Terms - obstetric and embryonic period

Interestingly, at determining the duration of pregnancy by menstruation in the first 2 weeks, there is no such period of pregnancy as such, because conception has not yet taken place.

Another way to calculate the term is by conception. It is also called embryonic period or true. Most often, it is difficult to say exactly when the conception occurred - the union of the egg and sperm - rather, we can talk about the known date of ovulation or proximity, as a result of which a new life was born. Such terms can be indicated in the ultrasound protocol or on the results form (hCG). Clarify this point to avoid confusion and unnecessary worries.

Correction of the obstetric period for late and early ovulation

Determining the gestational age by ultrasound

A good help in determining and clarifying the timing of pregnancy is.

Table 1. Coccyx-parietal dimensions of the embryo/fetus in the first trimester of pregnancy

Pregnancy period, weeks	KTP value, mm

In the II and III trimesters, several indicators are used at once to determine, but rather to clarify the timing of pregnancy using ultrasound. This is the biparietal size (BPR) - the size between the temporal bones, the circumference of the abdomen (OC) and the length of the femur / thigh length (DB).

Table 2. Fetometric parameters in the II and III trimesters of pregnancy

Pregnancy period, weeks	Biparietal size, mm	Abdominal circumference, mm	Femur length, mm

The greatest accuracy in determining the duration of pregnancy in the II and III semesters gives the complex use of the three parameters indicated in the table. Modern ultrasound machines independently calculate the period, taking into account all these indicators.

It must be remembered that the longer the gestational age, the more the size of a particular baby may differ from the “table” ones - individual traits begin to appear more and more clearly. So, before the 11th week, the measurement of CTE gives an accuracy of ± 2-3 days, after the 11th week - 2-5 days, before the 20th week, the measurement of BDP can give an error of up to 7 days, and after this period - up to 11 days . Therefore, you should not panic if your child's indicators differ from the average by a couple of millimeters, and at a later date by a couple of centimeters.

Determining the expected date of birth (ED)

So, in order to calculate when to expect the birth of a baby, 280 days (or 9 months and 7 days) must be added to the first day of the last menstruation. It is a little easier to count backwards - from the date of the first day of the last menstruation, you need to subtract 3 months and add 7 days. In this case, do not forget to add one year. This is a brain workout.

There are many services on the Internet where, by entering the start date of the last menstruation, you will receive an accurate calculation of the expected due date.

In fact, not many women give birth on this scheduled day. It is considered that the child was born at term if the birth occurred from the 38th to the 42nd week of the obstetric term. So your baby has a lot of choice when exactly to be born.

Each representative of the fair sex, having learned that she is in a position, seeks to calculate the exact gestational age as soon as possible. According to it, you can calculate the approximate date of birth of the long-awaited baby. Determination of the gestational age is also required by the gynecologist to track the development of the fetus, identify violations, and timely prescribe tests and examinations.

How do doctors determine the duration of pregnancy?

For women who come to a medical facility and claim to be pregnant, the gynecologist first of all asks when the last menstruation was. It is from this date that he will count. Interesting, right? Fertilization has not yet come, since it occurs during ovulation in the middle of the cycle, and obstetricians start counting from such an early date.

This method of determining the duration of pregnancy and childbirth is called " obstetric». True the period of an interesting position is about 2 weeks less than the period that the doctor tells the pregnant woman. The minimum period for determining pregnancy by this method is 2-3 weeks.

You can find out the period by the results of ultrasound. Their accuracy will be less in the later stages, because each baby develops in the mother's tummy in its own way. The doctor determines the gestational age by the size of the fetus. The following indicators are measured:

biparietal size, determined between the temporal bones (BDP);
fronto-occipital size (LZR);
head circumference (OG);
abdominal circumference (OC);
thigh length (DLB);
chest diameter (DRD), etc.

Each week is characterized by certain values of the above criteria. The gynecologist uses a special table for determining the timing of pregnancy to calculate.

The doctor can determine the term of an interesting position by the size of the uterus during a gynecological examination. For example, at the 4th week of pregnancy, the organ can be compared with a chicken egg, and at the 8th week - with a goose egg. Later, it is difficult to establish the term according to the size of the uterus.

How else do doctors determine the duration of pregnancy? For example, a method is used to determine the duration of the position along the length of the uterus. A tazomer or centimeter tape is used. As a rule, the number of weeks is equal to the length of the uterus. For example, during the measurement, it turned out that the length of the uterus is 34 cm. This means that the period is 34 weeks. To obtain reliable results, a woman is advised to empty her bladder before visiting a doctor.

How to determine the gestational age at home?

A pregnant woman can independently calculate the duration of her interesting position without the help of doctors. How to find out the gestational age at home? There are several ways:

according to the last menstruation;
by date of conception
at the first stirring of the crumbs;
using an online calculator.

1. How to determine the gestational age by the last menstruation?

The easiest way that doctors and many women find out the gestational age is by the last menstruation. How to determine the most gestational age by the last menstruation? Between the date of the beginning of menstruation and the date of the calculation, it is necessary to calculate the number of weeks. This will be the duration of the pregnancy.

By the date of the last menstruation, it is convenient to calculate the date of birth. There is a special Nagel formula. From the date of the last menstruation, 3 months are counted back and 7 days are added.

The calculation of pregnancy by the last menstruation is a fairly simple, but inaccurate method, since it is a couple of weeks longer than the true period.

2. How to determine the gestational age by the date of conception?

Recall that conception occurs approximately in the middle of the cycle after the release of a mature egg from the ovary (ovulation) during the day. The method of calculating the gestational age by the date of conception is suitable for those women who know exactly when they ovulated. The gestational age is determined by weeks. The countdown is from the date of ovulation. Average values can also be used (for example, with a 28-day cycle, ovulation approximately occurs on day 14, i.e., in the middle of the cycle). And how to determine the gestational age with an irregular cycle? In such cases, approximate values \u200b\u200bare not suitable.

The moment of release of an egg ready for fertilization can be determined using special tests, basal temperature or ultrasound results. Some women determine ovulation by how they feel (by the presence of pain in the lower abdomen, abundant discharge from the penis, increased libido). If the date of ovulation (and, accordingly, the date of conception) is unknown, then using the method of determining the gestational age by the date of conception will not work, since the results will not be accurate.

3. How to determine the gestational age by the first movement?

The baby begins to move in the tummy of the mother, whose pregnancy is the first, from the 20th week. Multiparous women begin to feel movements from the 18th week.

It is worth noting that using this method it is not always possible to find out the exact time. Some women feel the first movements much earlier than the indicated weeks, and some vice versa later. Most doctors note that the fair sex often confuses the first movements with the "work" of the intestines, because it is known that many pregnant women suffer from increased gas formation.

4. How to determine the gestational age using a calculator?

To calculate the gestational age, you can use the calculator, which is presented below. His work is based on the method of determining the period by the last menstruation, which was described above. How to determine the gestational age using an online calculator? In order to use it, you need to know the date of the beginning of the last menstruation, the average duration of the menstrual cycle and the luteal phase. The results of the calculation will be known immediately.

Summing up all of the above, I would like to note that many women are interested in the question of how to accurately determine the gestational age. However, with almost all of the above methods, it can not be calculated accurately. The only exceptions are cases when a pregnant woman knows the exact day of ovulation. Is it necessary to know the absolutely exact term of an interesting position? It is worth noting that it is not so important. Deviations of a few days or a week will not play a big role, so do not be afraid if the exact day of ovulation and conception is not known.

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