How to set the exact gestational age. Determining the gestational age. How to correctly and accurately determine the gestational age. Why you can not navigate by the day of sexual intercourse

Pregnancy is a long-awaited moment in a woman's life. From the moment of conception, the expectant mother already wants to know the date of birth of her baby.

Everything here is not always clear and unambiguous. For example, here is one of the questions I receive daily:

“Tell me, please, I’m pregnant, according to my monthly period I should give birth on September 24, according to ultrasound at 18 weeks, they set the date for October 16, the second ultrasound at 33 weeks is set for October 11. But when I was filling out the documents for the maternity hospital, they sent me for another ultrasound, and it showed September 30th. How can this be and what should I do, go to save now or wait until it grabs? Thanks in advance".

How to accurately determine the gestational age?

Different methods are used to determine the gestational age and date of birth.

Determining the gestational age and date of delivery by the date of the last menstruation

Usually the first thing the gynecologist asks at the appointment is the date of the last one.

In obstetrics and gynecology, the cyclicity and regularity of menstruation is an indicator of a woman's health.

In order to track the regularity of menstruation, a woman needs to keep her .

The most common way to determine the date of birth is the method by the date of the last menstruation.

The starting point is taken first day last menstruation. 40 weeks or 280 days or 9 calendar months or 10 lunar months are counted from this day - this will be the approximate date of birth.

The date of birth by this method is still determined according to the Negele formula: from the first day of the last menstruation, it is necessary to count 3 months ago and add 7 days to this date. This will be the date of the expected birth.

For example, the first day of menstruation was October 1st. We count back 3 months from this date (September 1, August 1, July 1 and add 7). It turns out July 8 - the estimated date of birth.

ATTENTION! This is only the estimated date of birth, because. many women give birth a little earlier or later than this date.

What does it depend on? From many factors. From the course of pregnancy itself, from the maturity of the child, from the readiness of the mother's body for childbirth, from diseases that aggravate pregnancy.

Determination of the term of childbirth by the date of ovulation

Determining the gestational age and date of birth by ovulation is more accurate. From the date of ovulation, count the past weeks - this will be the gestational age by the date of ovulation.

If you know the day of your ovulation, then add 273-274 days to this date and get the estimated date of birth.

Determining the due date by the date of conception

This is a more accurate way if you know for sure date of conception or sexual intercourse, especially if it was the only one. From the moment of conception to the moment of birth, 266 days must pass.

Add 266 to the date of conception and you get the estimated date of birth. It will also be approximate, because exactly day of conception hard to know.

What other ways are there to determine the gestational age?

Determining the gestational age by ultrasound

From the moment the ovum is immersed in the uterine cavity, with the help of an ultrasound machine, it is already possible to see signs of pregnancy. They are determined by the size of the uterus, by the size of the fetal egg, by the size of the embryo. At later dates - along the length of the thigh, the length of the shoulder, the size of the head and abdomen of the child, the thickness of the placenta.

There are special tables according to which the doctor calculates the gestational age by comparing the data obtained.

Determination of the gestational age by the height of the fundus of the uterus (VDM)

At later dates, starting from 14-16 weeks, the uterus comes out of the small pelvis and is already palpable above the woman's bosom. The doctor measures the height of the uterine fundus with a centimeter tape.

As a rule of thumb, WMD in centimeters = gestational age in weeks. For example, WDM = 16cm, which means that according to WDM, a woman is 16 weeks pregnant.

Determination of the gestational age by gynecological examination

Examination by a gynecologist is one of the accurate methods for determining the duration of pregnancy. Normally, the uterus has dimensions of 3x4x5 cm. During pregnancy, the uterus increases in size, becomes rounded, soft, and its anterior-posterior size increases.

When setting the gestational age, the gynecologist focuses on the size of the uterus. They are measured in weeks of pregnancy. For example, uterus the size of a newborn's head- This is 12-13 weeks of pregnancy.

Determination of the term of childbirth by the first movement

The primiparous woman begins to feel the movement of the child from the 20th week of pregnancy, and the multiparous - from the 18th week.

The doctor will ask you to remember the date of the first movement. From this date, 20 weeks are counted for primiparous and 22 weeks for multiparous and an approximate date of birth is obtained.

Sometimes women begin to feel a stir from an earlier date. For example, from 15 weeks. But in this case, the calculation of the date of birth will be very inaccurate.

In practice, to determine the gestational age and due date, the doctor will use ALL of these methods.

If there is a discrepancy between the size of the child and the gestational age, then this means signs of intrauterine growth retardation of the fetus and requires special treatment.

Thus, in order to establish the correct gestational age and determine the date of birth, a lot of calculations, measurements, and calculations are required.

Currently, the date of birth is very often determined by the doctors themselves or pregnant women when they decide that the pregnancy should end with a caesarean section, but more on that next time.

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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.

Having learned about pregnancy, a woman will certainly try to calculate the term and find out the approximate date of birth of the crumbs. But apart from idle curiosity, such calculations are extremely important from the point of view of medicine. A correctly calculated gestational age will help the doctor timely detect deviations in the development of the fetus. In addition, on the basis of the data received, a preliminary date of birth (PDR) is set. But it is worth considering that no one can calculate the exact date the baby was born, since pregnancy is an individual process, which is influenced by a large number of external unforeseen factors. Nevertheless, even not entirely accurate indicators help the doctor to correctly conduct professional monitoring of the expectant mother. How to find out the gestational age and can you do it yourself at home? The answers to these questions can be found in our material.

True pregnancy - what is it?

In order to correctly determine the gestational age, it is important to understand what indicators are taken as the basis. First of all, you need to know how long a normal pregnancy lasts. There is no consensus on this issue, since for some women normal natural childbirth can begin at 35 weeks, for others at 43, and in both cases the process is not considered pathological, and the child is born viable and healthy.

But as a result of research, it was found that in 70% of cases, a normal pregnancy lasts 38 weeks. This countdown is from the day of ovulation. This means that it is difficult to calculate the gestational age with an accuracy of one day, since not all women have a regular menstrual cycle, ovulation does not always occur in its middle, it is not known how quickly fertilization occurred, and how long the egg went down into the uterus.

The above 266 day pregnancy calculation assumes a 28 day female cycle with ovulation on day 14. But such an ideal situation is rare, so you can only know the gestational age approximately.

What is "obstetric weeks"?

As mentioned above, it is almost impossible to determine the exact date when conception occurred. Therefore, for the convenience and simplicity of calculating the gestational age, the concept of "obstetric weeks" was introduced. What is it? This calculation of the gestational age is not from the day of ovulation, but from the first day of the start of the last menstruation. That is, these indicators will differ from the true period by 2 weeks. So, if a period of 38 weeks was indicated, then, according to obstetrics, it is 40 weeks. It is in this way that the term is set in the antenatal clinic, the DA is also determined.

How long is the pregnancy - 9 or 10 months?

You can often hear from obstetricians about a pregnancy that lasts ten months instead of the well-known nine. The fact is that doctors do not mean calendar, but lunar months. They are 28 days, that is, exactly as long as the average menstrual cycle of a woman lasts.

Why is it important to know the gestational age?

Why is it important to know the gestational age? Such data are necessary for the gynecologist to correctly assess the development of the fetus and the course of pregnancy. At each period, standards for medical measurements have been developed, for example, determining the weight of a pregnant woman, abdominal circumference, etc.

Is it possible to intuitively determine pregnancy?

Often, women are interested in: is it possible to feel pregnancy even before the delay of menstruation? There is no scientifically based answer to this question. But often expectant mothers note that even before the tests they knew about their condition. Hypersensitivity, mood swings, changes in the consistency of cervical mucus are noted. But you should not rely on such symptoms - they can be caused by other reasons.

How long can you feel pregnant? Only one thing can be noted here: such important states, which, in principle, are difficult to miss, will testify to an interesting situation. This is the absence of another menstruation, the manifestation of toxicosis (at 8-12 weeks), as well as the feeling of intrauterine movements of the baby at about 20 weeks.

How to find out the gestational age by the menstrual cycle?

Calculating the estimated day the baby will be born according to the menstrual cycle is the easiest way to calculate. The gestational age by the date of the last menstruation is easy to determine on your own. You just need to count how many weeks have passed since the first day of the last period. The resulting indicators are the "obstetric" weeks of pregnancy. And if you subtract 2 weeks from these calculations, you get the true gestational age. Although it is not worth saying that these are accurate indicators, given the possible errors in determining the day of ovulation and the date of conception itself.

Are gestational age calculations based on knowing the exact day of conception reliable?

There are cases when a woman knows for sure when conception occurred (for example, if there was only one intimate relationship for the entire monthly cycle). But even in such a situation, it is impossible to calculate the gestational age to the nearest day, since spermatozoa remain viable for a week.

Ovulation and conception

And yet you can find out the gestational age by conception. The error is several days. When a couple is planning a child, a woman can monitor the onset of ovulation using the temperature, cervical method, or using express tests.

What is ovulation? This is the release of the egg from the follicle for further fertilization and attachment in the uterus. After ovulation, the egg is viable for only a day. It is at this stage that it is fertilized by a spermatozoon, which means that conception occurs. Thus, knowing the date of ovulation, it is easy to calculate how many weeks have passed since that moment. The results obtained are the beginning of the gestation period. And in order to determine the "obstetric weeks", you need to add another 14 days.

Examination by a gynecologist

Starting from the fifth week, the doctor can almost accurately determine the gestational age. An important indicator in this case is the size of the uterus. The fact is that even at such a short time, the mentioned body increases in size. Doctors have developed norms on the basis of which the term is determined. When a woman first visits a gynecologist, the doctor conducts an examination, including determining the size of the uterus. Thus, a short term pregnancy is calculated.

Fundal measurements

Starting from the 12th week of pregnancy, the need for a gynecological examination in order to determine the term disappears. Because this method becomes unreliable. At this stage, doctors move on to measuring the height of the uterine fundus. At this time, this reproductive organ is so enlarged that it extends beyond the pelvis, becomes visible to the naked eye.

How is the uterine fundus measured? For this, the pregnant woman is invited to lie down on the couch. Then, using a centimeter tape or a special tazometer device, the distance from the pubic symphysis to the highest point of the uterus is measured. The obtained indicators are compared with a table containing the norms for each trimester. Speaking conditionally, the resulting indicator is equal to the gestational age. For example, at week 12, the height of the uterine fundus is 12 cm. But such data are extremely approximate, since other factors influence the indicators, for example, multiple pregnancy, the amount of amniotic fluid, the individual structural features of the woman's body, etc. It should also be taken into account that measurement should be carried out only with an empty bladder, violation of this recommendation will lead to a false result.

The gynecologist records the data obtained in the pregnant woman's card in order to analyze the indicators in dynamics. With subsequent measurements, it is possible to indicate the gestational age with high accuracy.

Baby's first movement

A rather conditional way to calculate the gestational age is to determine the date of the first intrauterine movement of the child. Primiparous women may notice weak tremors around the 20th week of pregnancy, and multiparous women usually feel the baby's movements earlier - at 17-18 weeks.

Despite the fact that the gynecologist will definitely ask the woman about the date of the first pronounced sensation of the baby moving and enter the data into the exchange card, such information cannot be considered reliable when determining the gestational age. Since intrauterine development is an individual process, as well as the sensitivity of a woman.

Analysis for chorionic gonadotropin

Chorionic gonadotropin is also called the "hormone of pregnancy." It appears in the body of a woman at conception, ensuring the normal attachment of a fertilized egg and the production of progesterone. It is on the basis of the presence of hCG that most rapid tests determine pregnancy.

The hormone is produced up to 8 weeks, increasing literally twice daily, and in the presence of multiple pregnancy - in proportion to the number of future babies. Then the hCG levels stop increasing, and by the second trimester they begin to decrease.

Thus, by passing a blood test for the determination of hCG, you can find out the gestational age (up to 8 weeks). The results form will indicate the quantitative indicator of the hormone and its compliance with the standards.

Electronic rapid tests to determine the duration of pregnancy

At home, girls quite often use a pregnancy test. You can find out the term using modern innovative electronic test systems. They are based on finding hCG in the urine. Such tests are easy to carry out on your own, they are easy to purchase at the nearest pharmacy. And already a few minutes after the simplest procedure, you can find out the true term.

The most popular is the Clearblue electronic test. The method of its application is no different from simple "strips" to determine an interesting position. But in addition to the cherished "+" or "-" with its help, you can find out the gestational age by week. On the screen of a modern device, "1-2", "2-3" or "3+" will be indicated.

Ultrasound procedure

Ultrasound diagnosis with a high degree of probability allows you to find out if pregnancy has occurred. Terms, the sex of the baby are also determined using this method. This is a mandatory procedure for a pregnant woman, starting at 12 weeks. Although the doctor necessarily indicates the approximate date of conception with each ultrasound, it is highly likely that you can find out the gestational age only in the first trimester. Since it is during this period that the fetal egg develops relatively equally in most women. By measuring the uterus, the volume of amniotic fluid and the size of the embryo, doctors establish the correspondence of the obtained parameters to the gestational age.

Often, women wonder if it is possible and how to feel pregnancy before a delay in menstrual flow. You can, of course, listen to your inner feelings, but ultrasound will give a clear answer even at the earliest possible date (from the day a fertilized egg is attached to the uterus). That is, long before the expected menstruation, the doctor can detect a fetal egg on the monitor screen, take measurements and determine the date of conception.

Online Applications

By the way, did you know that you can calculate the gestational age using special electronic calculator applications? The essence of the process is to calculate the duration of the menstrual cycle and determine the date of ovulation. In principle, you can calculate the indicators yourself. But the online application will do it in a matter of seconds, taking into account various factors and determining the term with high accuracy. So, what is required of a mother?

To calculate the gestational age using a special calculator, you must fill in such columns as "the first day of the last menstruation" and "cycle duration". As you can see, everything is quite simple. True, some applications calculate the true gestational age, others - obstetric.

Summing up

Determining the gestational age allows not only to satisfy idle curiosity, but also to calculate the expected date of birth, as well as to detect deviations in the development of the fetus in a timely manner. After all, with many pathological conditions, timely and proper medical care will help preserve the health, and sometimes the life of the unborn baby and his mother.

Update: October 2018

Any woman who is preparing to become a mother is looking forward to the appearance of two cherished strips on the test. After this moment, excitement and anxiety arise. Is the baby developing normally when you need to go for the first ultrasound, and, finally, when is the birth coming? All these questions can be answered by knowing the exact gestational age.

What is the gestational age?

Very often, confusion in the head of a pregnant woman arises from a misunderstanding of this term. Therefore, it is important to know when the development of the embryo begins, and when the countdown to birth begins.

The egg after ovulation (exit from the ovary) lives for about a day. It is this time that is considered the most favorable for conception. With a menstrual cycle of 28 days, ovulation occurs on the 14th day. At the time of fertilization, the sperm fuses with the egg, and a week later the developing embryo attaches to the inner lining of the uterus.

Since in most women the length of the menstrual cycle is not constant, no one knows the exact date of ovulation and conception. Therefore, all obstetricians in the world are considered to be the beginning of pregnancy on the first day of the last menstruation. After 9 months (280 days) after this day, childbirth should take place. This is the paradox: the countdown of pregnancy has already begun, but conception has not yet occurred. Therefore, the life of the embryo is less than the gestational age by an average of 2 weeks.

Methods for determining the gestational age and date of birth

All doctors in the world determine the duration of pregnancy by one main parameter (ultrasound) and two auxiliary ones (date of menstruation and examination of the pregnant woman).

ultrasound

The main method is ultrasound. It is important to remember that the accuracy of this method is maximum in the first 10-12 weeks, and then it drops. Therefore, it is ultrasound of the first trimester that is widely used to determine the expected date of birth.

Modern devices can detect a fetal egg in the uterus from 3-5 weeks of pregnancy. As the embryo grows to 3-4 mm, it becomes possible to measure its KTP (coccygeal-parietal size), which serves as the basis for determining the gestational age to the nearest day. Usually, in the conclusion, the doctor indicates which period he means: obstetric (from the last menstruation) or embryonic (from the moment of conception).

After 22 weeks of pregnancy, it is impossible to accurately determine the age of the fetus. But the measurement of its main parameters (head size, femur length, abdominal circumference) allows us to evaluate the dynamics of growth. If it does not correspond to the period declared during ultrasound in the 1st trimester, then there is a possibility of fetal growth retardation syndrome. In addition, there are individual hereditary characteristics (short stature, large head), due to which, in the third trimester, the gestational age cannot be calculated by ultrasound.

Date of the last menstruation - calculation calculator

Determining the gestational age by the day of the last menstruation is the most affordable way for a woman. If the expectant mother is a happy owner of a regular cycle of 28 days, then she can independently and fairly accurately calculate the date of birth. There are special Naegele formulas for this.

PDR \u003d LMP - 3 months + 7 days

• EDD - estimated date of birth
• LMP - first day of last menstrual period

For example, if the LAP was on June 15th, then PDR = June 15th - 3 months + 7 days = March 15th + 7 days = March 21st. This is the basis for determining the date of birth in all special calculators for calculating the gestational age.

Gestational age is determined by adding to the LMP the number of weeks that have passed since that day. Therefore, every woman can calculate the gestational age using a regular calendar.

When is it impossible to determine the period for menstruation?

• Irregular menstrual cycle. With a cycle greater than 35 days, ovulation does not occur on the 14th day. Therefore, the Negele formula will give an inaccurate result (see).
• Taking birth control. If the regularity of taking oral contraceptives is not observed, pregnancy may occur. Due to sudden ovulation, the formula for calculating the EDD is also not suitable (see).
• With the threat of termination of early pregnancy. It happens that there is a threat of termination of pregnancy at the shortest possible time. Very often it is manifested by scanty spotting on the days corresponding to the expected menstruation. That is, a woman can confuse bleeding at the 5th week of pregnancy and regular menstruation, and will not even guess about her interesting position. In such cases, the period is determined using ultrasound.

Examination of a pregnant woman

The registration of each pregnant woman in the antenatal clinic begins with an examination. Determining the size of the uterus and the height of its bottom (that is, the upper part) can provide indicative information about the gestational age. This method is not 100% accurate. After all, the individual location of the uterus, fibroids and a full bladder can make it difficult to examine. A multiple pregnancy is associated with a large increase in this body.

HCG level

Already 8-10 days after conception, the B-subunit of hCG is determined in the blood of the expectant mother. This hormone appears during pregnancy and doubles every 2-3 days (see). It is possible to judge the gestational age by its level only indirectly.

• Firstly, the hCG rates for each week of pregnancy have a large range.
• Secondly, its level increases with multiple pregnancies and some anomalies in the development of the fetus. Therefore, it makes no sense to focus on this hormone when calculating the gestational age by weeks, when more accurate methods are available (ultrasound, for example).

Date of first movement

It is believed that nulliparous women feel fetal movements from the 20th week of pregnancy. Multiparous can feel them already from 16-18 weeks. In fact, it all depends on the individual characteristics of the mother and child, the thickness of the fat layer on the pregnant woman's abdomen and on her desire to feel the tremors. In addition, intestinal peristalsis is often taken as the first movement. Therefore, you should not rely on this indicator in calculating the gestational age.

How to determine the gestational age during IVF?

With in vitro fertilization, many women doubt how to correctly count the weeks of pregnancy. After all, an already developing embryo is planted in the uterine cavity. But regardless of the method of fertilization (naturally, sperm insemination or IVF), the gestational age is determined from the first day of the last menstruation. The only exception can be considered IVF with a menstrual suppression protocol (superlong protocol). In this case, the period is counted from the day of embryo transfer with the addition of two weeks.

Why do doctors determine the exact gestational age?

• To assess the rate of fetal development
• To determine the date of birth
• For screening for chromosomal mutations (Down syndrome, etc.)
• To determine the viability of a child in preterm birth

The main goal of determining the gestational age for the expectant mother is to tune in to the upcoming birth of the baby and get acquainted with information about intrauterine development by weeks.

When registering a woman for a consultation, the doctor must determine the duration of her pregnancy. Why is it necessary to know? In order to establish the expected date of delivery. Knowing the exact gestational age, the doctor can competently monitor the development of your baby, detect and correct possible pathologies in time. Let's take a closer look at how you can find out the duration of your pregnancy.

Before you talk about possible ways to determine the age of the fetus, you need to make a reservation that there are two stages of pregnancy: obstetric and true. Obstetricians take into account the first day of the last menstruation, which becomes the reference point for the gestational age. The true gestational age is counted from the day of conception and lags behind obstetric by 2 weeks.

For example, if you came to the antenatal clinic with a delay of 5 weeks, do not be surprised that the doctor will give you 7 weeks of pregnancy. You can read more about each of the methods for determining the gestational age below.

The conception of a child coincides with the day of ovulation, because after leaving the ovary, the egg remains viable only for a day. Ovulation has quite characteristic symptoms: tingling in the ovaries and abdomen, clear mucous discharge from the genital tract, strong sexual desire.

The day of ovulation can also be determined using special tests that are sold in pharmacies. Some women use the old proven method:. Rectal temperature is measured in the morning at the same time; during measurements, the woman should not get out of bed. Around the middle of the cycle, the temperature rises above 37 degrees, which indicates that ovulation has occurred.

To determine the duration of pregnancy, you should not take into account the day of sexual intercourse. It does not necessarily coincide with the date of conception: once in the uterus, spermatozoa can live there for up to 7 days, waiting for the egg to be released from the ovary. Therefore, in order to get pregnant, it is better to have intimacy a few days before ovulation than after it.

The date of the last menstrual period is taken into account by obstetricians around the world to set the exact gestational age. All the doctor needs to know from you is the date of the first day of your last period. From this moment, the period of your pregnancy begins to count. This method can be considered quite accurate, because it is from the first day of the menstrual cycle that the egg begins to develop, which will then be fertilized by the sperm.

If a woman has an irregular menstrual cycle, then the doctor uses additional methods to determine the exact gestational age: examination, ultrasound, hCG analysis.

A test will help determine the exact gestational age even before going to the antenatal clinic. The principle of operation of digital pregnancy tests is the same: they detect the presence in the urine hCG - human chorionic gonadotropin. This hormone, which begins to be produced by the body only during pregnancy, is simply absent in non-pregnant women. From the moment of fertilization of the egg, its number doubles every 2 days and reaches its maximum at 8-10 weeks of pregnancy.

The best time to test is in the morning when urine is most concentrated. However, there are inkjet tests that are highly sensitive. They can be done at any time of the day. After urine is absorbed into a special strip, the test will begin its work. After a few minutes, the test result will appear on the LCD screen, indicating the possible gestational age. Usually the test has 3 options: 1 - 2 weeks, 2 - 3 weeks, 3 weeks or more.

Ultrasound procedure

The most reliable method for determining the duration of pregnancy at an early stage is ultrasound (ultrasound). Up to 7-8 weeks, in most women, the embryo grows at the same pace, so its size will be approximately the same. This is the only method that allows you to exclude frozen and ectopic pregnancy and find out the location of the fetus.

During the next ultrasound (at 20 and 30 weeks), the size of the fetus in women of different ages and with different body weights will differ. The ethnicity of the patient, the weight of the mother and father at birth, etc. also play a significant role. Thus, at a later date, babies develop very individually and can have different sizes at the same time.

Gynecological examination

At the first visit to the antenatal clinic, the doctor conducts a gynecological examination. It helps to determine the approximate gestational age, to find out the location of the fetus. During pregnancy for up to 6 weeks, the uterus is slightly enlarged. At 8 weeks, it becomes the size of a goose egg, and at 10 weeks it is already the size of a woman's fist. When the gestational age reaches 12 weeks, the doctor, during an external examination on the couch, using a centimeter tape, easily determines the height of the uterine fundus.

By fetal movement

The first movement of the fetus is not a very accurate term for determining pregnancy. Usually, pregnant women begin to feel the movements of the baby in the womb at 18-20 weeks, but thin patients can feel it a little earlier - from 16 weeks.

How to calculate the gestational age?

The total duration of pregnancy is 280 days or 10 lunar months

You can find out the date of birth using a simple formula: - 3 + 7. Subtract three months from the first day of the menstrual cycle and add 7 days. The resulting date will be the approximate date of birth.

Usually, a gynecologist uses not one, but several methods to determine the gestational age, which increases the accuracy of the calculation.

The most reliable methods are considered to determine the gestational age by ultrasound and the day of ovulation (conception)

Quite often it happens that the date of birth of the baby does not coincide with the date set by the doctor. The reason for this is not at all a mistake, but the fact that the period of intrauterine development of the fetus can be from 38 to 42 weeks. It depends on a large number of factors, including the genetics of the patient.

That is why at the first appointment, the doctor usually asks the question at what time the father of the child and the woman herself were born. So if your baby was born a little earlier or later than the term prescribed by the doctor, you have no reason to worry.