How is the gestational age determined by ultrasound? When can pregnancy be determined by ultrasound: at what stage is the fertilized egg visible? Can a doctor make a mistake?

It is possible to calculate the gestational age using ultrasound at an early stage with an accuracy of up to several days, which is especially important if the pregnant woman has made a mistake in the date of her period, and the amount of the hCG hormone does not coincide with the numbers prescribed for this period. It is necessary to determine the duration of pregnancy to timely determine various pathologies and the date of birth. How accurately an ultrasound determines the gestational age depends on when the woman came for her appointment. The earlier the better.

It is necessary to understand that even in the modern world of advanced technologies, a doctor can make a mistake in determining the duration of pregnancy, despite the ultra-modern equipment. One of the reasons for this is the individual characteristics of both the mother and the fetus.

However, it is now more possible to accurately determine the date of birth than in the pre-technological era, when people made mistakes much more often, since the start of pregnancy was counted from the first day of the last menstrual period (gestational age or obstetric period). This is the reason why, according to most doctors, an official pregnancy lasts 40 weeks. But in reality it lasts 38 weeks, that is, 2 weeks shorter, since conception occurs in the middle of the cycle.

If we approach this issue historically, then obstetricians took into account the first day of menstruation primarily because the flow of menstrual blood is a rather dramatic process for a woman and it is much easier to remember or mark the start/end date on the calendar. In addition, there is a good chance that the doctor is not mistaken about the gestational age when the report starts from the date of the start of menstruation.

Another way to determine the day of pregnancy is when women calculate the time using a calculator. There are many calculators on the Internet that can help you determine the date of conception. To do this, you only need to enter a few values, the date of your last period and the length of your cycle. Of course, what such a calculator can show is significantly inferior to ultrasound in terms of calculation accuracy.

What does ultrasound determine?

Determining the gestational age using an ultrasound is much more accurate than using a calculator or period-based reading. It is known that people can make mistakes when relying on the values ​​they put in the tables. The probability of error is especially high when there is a large amount of data.

But the errors are much smaller when a computer calculates. Modern ultrasound technology with the latest computer and software is able to take into account many parameters when determining the date of conception. In this case, the procedure for determining the date of conception and the date of probable birth is performed automatically, after which the ultrasound shows the ready-made values.

However, older generation ultrasound machines without modern software can be used to determine the date of conception. When performing an ultrasound, the doctor receives the following information:

• Number of fetuses and gestational sacs.
• Presence of fetal heartbeat.
• The dimensions of the fetus, from which the estimated gestational age is calculated.
• Abnormal features of the uterus, including abnormal shape and fibrous tissue.

Most ultrasounds are done transabdominally (through the skin of the abdomen) with a full bladder. If the pregnancy is up to six weeks, transvaginal ultrasound is used, which gives a better picture, since the fetus and fruit sac are not yet sufficiently developed at this time. During the examination, the bladder must be empty, and the method involves the use of a vaginal sensor.

How is the term calculated using ultrasound?

During the examination, you can see the following images on the ultrasound monitor, characteristic of a certain period:

• When an ultrasound scan is performed at 5 ½ weeks of gestation, a small fetal sac can be seen, but neither the embryo nor its heartbeat is visible. When the radiologist says 5 ½ weeks of gestation during an ultrasound examination, this is counted from the first day of the last menstrual period, which corresponds to 3 ½ weeks from conception.
• From 6 to 7 weeks of gestation, the fetus is clearly visible on transvaginal ultrasound. In addition, his heartbeat is visible - from 90 to 110 beats/min. As the embryo gets older, the heart rate increases to 110-200 beats.
• At 8 weeks of gestation, the baby and its heartbeat are easily determined by both transvaginal and transabdominal ultrasound.

In the first trimester, an ultrasound scan first of all determines that the fetus is alive and establishes its age by measuring the length of the body from the crown to the beginning of the spine. Such measurements are a reliable indicator of the gestational age of the fetus. Therefore, this is the main method of how ultrasound determines the gestational age.

There are many tables for calculating age depending on this length. But there is a simple rule that from 6 to 11 weeks the embryo grows at a rate of 1 mm per day. From this, the gestational age of the embryo can be calculated. It is equal to 6 weeks + the number of millimeters from the crown to the coccyx, expressing days.

For example, if the embryo measures 23 mm between 6 and 11 weeks, its age is:

6 weeks + 23 mm (or 23 days) = 6 weeks. + 3 weeks +2 days = 9 weeks and 2 days

Based on these values, the date of birth is calculated using ultrasound. The accuracy of calculations of what period is indicated by ultrasound decreases after 12 weeks and is replaced by calculations using measurements of the size of the embryo's head (biparietal diameter). But it should be expected that with such a duration of pregnancy, an error is possible: according to ultrasound, the period may be longer or shorter.

Should you trust ultrasound?

How accurately an ultrasound determines the gestational age depends on what time the diagnosis is made. An ultrasound to determine the due date, which was performed at 12 weeks of pregnancy, usually has an error of 3-5 days. The most accurate is ultrasound from 8 to 11 weeks of gestation, since at this time the fetus develops very quickly and changes in its size are visible, which are used to determine the period. In addition, at this time the fetal body is easier to measure because it does not bend or twist in the same way as is typical at a later age.

Ultrasound after 22 weeks of gestation cannot be used at all to calculate the due date, since during this period the size of the baby and its age are no longer related. The magnitude of the error with the gestational age at this stage is very large and amounts to 2-3 weeks. In this case, the term according to ultrasound is often set to be greater than the obstetric term, or the term according to ultrasound is less than the obstetric one.

Thus, if a pregnant woman wants to use ultrasound to calculate her due date, the most accurate days will be around the 8th week of pregnancy. In this case, it is advisable to use the latest equipment: with outdated equipment, only an experienced sonologist can accurately determine the gestational age using ultrasound. At the same time, when examining using new equipment, much depends on the quality of computer software and equipment. Therefore, the point is not whether ultrasound can be wrong, but by how much and why.

Search for pathologies

In addition to determining the timing of pregnancy by ultrasound, during the examination the doctor needs to check for certain abnormalities in the baby. Diagnosis for the presence of abnormalities is carried out between 10 and 14 weeks of pregnancy. This study is performed using transabdominal ultrasound. If the picture is unclear, a transvaginal examination may be necessary.

During an ultrasound, a complete assessment of the pregnancy is carried out, for which the amount of amniotic fluid, the position and type of the placenta, and a detailed image of the embryo are determined. The fruit is measured in all respects. The presence of chromosomal abnormalities is indicated by a rounder head shape, a short nasal bone, wide hands with short fingers and other signs.

Thus, an ultrasound aimed at searching for abnormalities is a very important examination. This is why doctors recommend that every pregnant woman have an ultrasound at 12 weeks. Even the first scan may show chromosomal abnormalities. For example, thickening of the collar zone (in the neck area), which makes one suspect Down syndrome and other genetic problems.

The transparency of the fetal nuchal zone is the amount of fluid that has accumulated under the skin in the back of the fetal neck. The word "transparency" is used here because in the image it appears as a black area just under the skin at the back of the neck. The amount of this fluid may increase with Down syndrome and other genetic abnormalities. Currently, ultrasound is the most reliable non-invasive method for determining Down syndrome in an unborn child between 11 and 14 weeks of pregnancy.

Echogenic sites in the heart also increase the risk of Down syndrome. To clarify the diagnosis, if the collar area is transparent, the presence of a pronounced nasal bone is checked. In 75% of fetuses with Down syndrome it is not clearly expressed. Therefore, a visible nasal bone reduces the likelihood of this pathology.

During the ultrasound test of the nuchal area, it is also checked whether the child has all the limbs, whether the head and brain are normally developed, whether the stomach and bladder are clearly visible, and whether the umbilical cord is positioned correctly. From the 12th week, ultrasound allows you to clearly view the spine to exclude an anomaly such as spina bifida.

If the fetal intestine appears bright and white (the same color as the bones), it is called echogenic intestine. Its appearance can be caused by various reasons, and increases the risk of a congenital disease such as chromosomal trisomy. The same pathology is indicated by the short femur and humerus, as well as the choroid plexus cyst, which is located in the fetal brain and disappears by the 28th week of pregnancy. If present, it increases the risk of chromosomal trisomy.

Ultrasound allows one to identify pathologies such as enlarged renal hilum (pyelectasis), which can subsequently lead to pyelonephritis. However, you shouldn’t despair right away: when asked whether an ultrasound can be wrong, many women who have given birth to a healthy child will give an affirmative answer. However, to confirm the diagnosis, it will be necessary to undergo additional examinations, after which the doctor will make a verdict.

In the first months of intrauterine life, embryo development occurs at a rapid pace. Almost every week the formation and development of internal and external organs and systems occurs. The future baby increases proportionally in size and weight. As it grows, its needs for certain chemical elements change, and a pregnant woman is prescribed folic acid, iodine preparations and certain diets. That is why to manage pregnancy it is necessary to know its exact duration. How to determine the gestational age?

Determining the gestational age by menstruation

Since menstruation stops with the onset of pregnancy, the date of the last discharge is the most common argument among obstetricians. The obstetric period is calculated from the first day of the last menstruation and is usually 14 days ahead of the actual gestational age, since ovulation occurs not at the beginning, but at the middle of the menstrual cycle. The method of determining the duration of pregnancy by menstruation is used to calculate the date of birth. To do this, take the start date of the last cycle, subtract three months from it, then add one week. This date, in turn, is necessary to calculate the duration of maternity leave. However, in rare cases, spotting may occur after conception, and this can seriously affect the result.

When calculating the gestational age, the moment of the first movement of the fetus can be taken into account, which occurs at 20 weeks for first-time mothers and at 18 weeks for the second and subsequent births. But this factor is very subjective, because some mothers do not immediately notice the movements, while some, on the contrary, mistake the work of the digestive organs for them. Therefore, the first movement can be a clarifying factor in determining the duration of pregnancy, but not decisive.

How to determine the gestational age by the size of the uterus

Up to 8 weeks, an obstetrician-gynecologist can, by examining the vagina, determine the gestational age with an accuracy of up to a week. To do this, the doctor palpates and evaluates the size of the uterus. At 4 weeks it reaches the diameter of a chicken egg, at 8 weeks - a goose egg. After 8 weeks, the size of the uterus may differ among different women at the same stage of pregnancy. Moreover, if the pregnancy is multiple, the uterus enlarges even more. However, for up to 8 weeks, the size of the uterus is a more reliable indicator than the previous ones.

How to determine gestational age using ultrasound

Ultrasound examination in the first months of gestation allows you to determine the age of the embryo with an accuracy of one day, but only up to 8-12 weeks. After this period, the accuracy of the method decreases significantly; for example, at 36-38 weeks, ultrasound can determine the gestational age only with an accuracy of 1-2 weeks. How to determine the gestational age using ultrasound in the first trimester? The fact is that ultrasound is an accurate method, but not absolutely ideal. When the embryo is barely 2-3 weeks old (which roughly coincides with the first days of the delay), the ultrasound machine can only see the fertilized egg, and if you try to take a picture of the uterine cavity, you can barely see a small dot. However, at such an early stage the device does not always detect the presence of an embryo. There is a much greater chance of seeing the unborn child on an ultrasound and assessing the gestational age after 4 weeks of gestation. Although during this period the size of the embryo is only 3-4 mm. What to do if you missed the first scheduled screening and you don’t know the exact date of conception? How to determine the gestational age by ultrasound in this case? In the second trimester, the main indicator is the size of the average internal diameter of the fetal egg, or the coccygeal-parietal size of the embryo. These data allow you to determine the gestational age with an accuracy of up to 6 days. In the third trimester, the size of the cerebellum is taken as the main indicator of fetal development.

How to determine the gestational age using hCG

HCG is an abbreviation that stands for human chorionic gonadotropin. HCG is a hormone that begins to be produced after the embryo is implanted into the wall of the uterus. How to determine the gestational age using hCG? Hormone production begins 6-8 days after fertilization of the egg and increases over time. It is the presence of hCG in the blood and urine that popular pharmacy pregnancy tests, both paper and electronic, react to. The hCG hormone is necessary to maintain a normal pregnancy. In the first weeks of gestation, its level can double every 2-3 days; this growth stops by the end of the second month of pregnancy, after which the level begins to gradually decrease. During multiple pregnancies, the hormone level increases in proportion to the number of fetuses, for example, with two fetuses - twice as much. Determining the gestational age using hCG will help when the ultrasound machine is not always able to see the fetus, but only if the embryo is less than 5 weeks old.

Clearblue with gestational age detection

Modern pregnancy tests allow you not only to find out whether your cherished 9 months have started, but also to determine how far along you are. And one of these tests is Clearblue, which determines the gestational age.

In appearance, it is similar to a regular digital test - the narrow end needs to be immersed in a container with urine for 20 seconds. If you have activated the test correctly, an hourglass icon will appear on the display. Now, within a few minutes, the test will show a plus in case of pregnancy and a minus in the absence of it. Under the positive result, after a few seconds, information about the period will appear - this can be 1-2 weeks, 2-3 weeks, or 3 weeks or more.

Clearblue, which determines the duration of pregnancy, is relevant already 4 days before the expected delay. Unlike strip tests, Clearblue gives a clear, clear answer that will be visible on the screen within 24 hours.

Each of the methods we have given for determining the duration of pregnancy is effective at its own stage. For example, in the very early stages, these are Clearblue and hCG tests. At a period of 5-8 weeks, this is an obstetric method for determining the size of the uterus. From 8 weeks onwards, the most reliable method is ultrasound.

It is generally accepted that during a normal pregnancy, its average duration in the population is about 280 days, if we count from the first day of the last menstruation which is called "obstetric gestational age". This calculation is used to determine the timing of prenatal leave and the expected date of birth, as well as to estimate the size of the fetus according to ultrasound data during pregnancy more than 12 weeks.

To determine the expected date of birth, according to the obstetric period, from the date of the first day of the last menstruation according to the calendar count back three months and add 7 days. However, it should be borne in mind that the expected due date is not a fixed date. This is just a certain period of time, amounting to ± 10-12 days, when labor is most likely to occur. The fact is that the gestation period for each woman in each of her pregnancies is strictly individual, varying within certain limits around an average duration of 280 days.

Sometimes they use the so-called calculation "embryonic period" pregnancy from the moment of conception, which is often almost coincides with the date of ovulation. The fact is that a woman’s menstrual cycle (the period from the 1st day of one menstruation to the 1st day of the next menstruation) lasts on average 28-30 days. During the first half of the menstrual cycle, a follicle matures in one of the ovaries, and ovulation occurs on days 14-15. In this case, a mature egg is released from the follicle. Taking into account that a mature egg is capable of fertilization within 2 days after ovulation, and sperm have fertilizing activity within 4 days after ejaculation, the total period of the most probable possibility of conception is about 6 days. The embryonic period is shorter than the obstetric period by approximately 14 - 15 days .

In clinical practice, doctors mainly use the calculation of the “obstetric period”, since most pregnant women know well when the first day of the last menstruation was, but not all of them have a clear idea of ​​the date of conception.

It is also possible to determine the gestational age by the size of the uterus and the movement of the fetus. However, these criteria are not precise, as they have a pronounced individual character. The fact is that the size of the uterus at the same stage of pregnancy varies widely among different women, which does not allow us to estimate the gestational age of each individual patient with an accuracy of up to a week.

The sensation of fetal movement is also very subjective and depends on the sensitivity threshold of each woman. So some women may, for example, begin to feel fetal movements from 18 weeks, while others only from 22 weeks. But in fact, the fetus begins to move from 7-8 weeks.

Quite typical and widespread is the misconception is that ultrasound is used to determine the gestational age. This doesn't actually happen. In the process of this study, another equally important question is solved - for what period of pregnancy are the fetal sizes obtained during the study typical, provided that the expected period of pregnancy is known, which, in turn, is calculated from the first day of the last menstruation or from the date of conception. Therefore, if in some observation, for example, it is known that the expected gestational age is 32 weeks, and according to ultrasound data, the size of the fetus is characteristic of a gestational age of 29 weeks, then no one will argue that the gestational age is 29 weeks and not 32. It will it was concluded that there is a delay in fetal size by 3 weeks, which will require a more in-depth examination to determine the reasons. In addition, in dynamics, ultrasound assesses the rate (speed of fetal growth) in accordance with the gestational age.

During the normal course of pregnancy, which occurs in most patients, the size of the fetus and the gestational age coincide, which creates a false assumption that ultrasound can determine the gestational age.

It is also important to take into account the following circumstances: up to 12 weeks of pregnancy, when the length of the embryo (its coccygeal-parietal size - CTE) and the average internal diameter of the ovum are assessed using ultrasound, the correspondence of the measurement results to the gestational age is assessed using tables calculated for the “embryonic period” ", which is 2 weeks less than obstetric.

At a later date, ultrasound is used to compare the results of fetal measurements using ultrasound. tables calculated for obstetric period(from the first day of the last menstruation).

If the doctor who conducted the study up to 12 weeks did not make an adjustment by 2 weeks for the obstetric period, then discrepancies of 2 weeks may arise between the gestational ages that were suggested by ultrasound data before 12 weeks and after. In reality there is no difference. You should only add 2 weeks to the result obtained before 12 weeks, if this has not been done.

Thus, the gestational age in weeks is determined only on the basis of a set of data, including the date of the last menstruation, the date of conception, dynamic ultrasound results, and data on the rate of fetal growth.

Modern women are very lucky. After all, relatively recently, pregnant women did not have the opportunity to see their baby before giving birth. With the development of medicine, this is now quite possible. At what stage does an ultrasound show pregnancy? This question worries every girl who has experienced a delay or has other symptoms that incline her to think about a possible case of fertilization. There is no point in immediately running to the doctors for the procedure; anyway, nothing will be visible yet. Therefore, you should be patient and wait a little. You can visit a gynecologist and ask him when an ultrasound will show pregnancy.

Embryo on ultrasound

Why do ultrasound examinations and what is its importance?

At the first signs of fertilization, the girl should contact the antenatal clinic to confirm her status and register. After all, medical supervision is very important during this period. For various reasons, pregnancy may not be confirmed: the test may show false data, or the cycle may simply go wrong for any other reason. The doctor, after examination, will confirm or deny this fact, but the presence of a fetus will definitely be shown by the first ultrasound procedure.

Why is it important to carry out this procedure after a delay? Let's look at the reasons in more detail:

• In case of prolonged absence of menstruation, it is possible to find out the true cause of the pathology if fertilization is not confirmed. After all, such a development of events can signal the development of a gynecological disease.
• In the early stages, pregnancy can be determined using ultrasound.
• Using an ultrasound, you can check whether the fetus is well attached, then assess its condition and rule out the development of any kind of anomalies.
• The procedure allows you to detect an ectopic pregnancy and protect the woman from the risk of harm to her health and life.
• Ultrasound examination is the only reliable source with which you can see fetal fading or a failed miscarriage.
• An ultrasound can save the child by showing in advance the threat of miscarriage due to increased tone or another reason. The doctor will prescribe the necessary therapy in a timely manner.

Ultrasound examination is an absolutely safe procedure, both for the unborn baby and for the young mother. All prejudices about its harmfulness are a complete myth.

At what period is ultrasound able to recognize the fertilized egg?

How many days after conception can you recognize the onset of an interesting situation? The egg is fertilized on the day of ovulation or a couple of days later. But for this it is important that the sperm reaches her. The egg travels through the fallopian tubes to the uterus, where it attaches to its mucous membrane. A woman feels a nagging pain in the lower abdomen, as before the onset of menstruation. From now on, she is a future mother.

First diagnostic ultrasound to confirm pregnancy

An ultrasound to determine pregnancy will show an accurate result if you follow a number of conditions and recommendations:

• the procedure can determine pregnancy and the number of fetuses 90% accurately only at 10 weeks, so it is worth observing the timing of visits;
• absence of inflammation (due to swelling, the device will not distinguish a tiny embryo);
• selection of the most suitable type of ultrasound examination.

At what time can the origin of life be determined? This can be done in the first weeks of fertilization (at 3 weeks of pregnancy), but the result may not live up to expectations. Therefore, it is best to wait and carry out. Of course, if there are no special health reasons for a premature examination.

In modern medicine, the process of determining pregnancy in the early stages is represented by two options for ultrasound examination: transvaginal And abdominal. Using the first type, pregnancy can be determined as early as 21 days after conception. It is performed by inserting a special sensor into the vagina. This is a fairly accurate survey with the least amount of error. The second type of study is capable of determining pregnancy 5 weeks after fertilization.

What ultrasound should be done to determine early pregnancy? A gynecologist will answer a similar question after examining and assessing the mother’s health.

Transabdominal and transvaginal ultrasound sensors

How to prepare for the pregnancy detection procedure?

Determining pregnancy by ultrasound requires that certain rules be followed in order for the results to be reliable. Gases in the intestines interfere with any research, so it is worth excluding legumes and other gas-forming foods from the diet. At least two days before the procedure.

When a transabdominal examination is ordered, the bladder must be filled. It is advisable to drink a sufficient amount of water three hours before the procedure, if the woman is able to tolerate that much. Because of this, discomfort may occur during the examination. It is impossible to accurately determine the gestational age using an ultrasound with an empty bladder.

If you are scheduled for a transvaginal procedure, have a bowel movement and avoid sex a couple of days before the test.

Is it necessary to conduct an ultrasound examination in the early stages?

Ultrasound shows pregnancy starting from 3 weeks. However, if there are no special appointments, then it is not worth carrying out the procedure at such an early stage at the individual request of the expectant mother. How to determine the gestational age, how many weeks have passed since the day of conception, if you do not carry out the procedure? The doctor will help the girl figure this out during an examination in a gynecological chair and based on test results.

Pregnancy should not be checked using a transvaginal ultrasound if a woman is bothered by aching pain and cramps in the lower abdomen, as well as during a period when periodic brown or red discharge is noted. Is it possible to use this method to detect the presence of a fetus in the early stages of pregnancy? Yes, this type of study determines conception quite accurately, but doctors often talk about the possible risks of damage to the embryo. Therefore, the procedure must be performed by an experienced doctor.

Can a doctor make a mistake?

It is possible to see pregnancy in the early stages, but sometimes an inexperienced diagnostician can confuse it with a hematoma or other neoplasm. Determining the gestational age or sex of the child can be erroneous. The reasons for this are the following:

• short period of time;
• the presence of hematomas and other formations;
• old, poorly functioning equipment;
• non-professional physician conducting research.

Error cases are quite rare. Almost always, ultrasound can detect the presence of a fetus. How many days later can the procedure be repeated? A specialist will inform you about this at your appointment.

At what stage will an ultrasound show pregnancy? First planned The procedure is carried out at the 10th week of an interesting situation for a representative of the fairer sex. But the fertilized egg can be seen after 5 days of absence of menstruation. What kind of ultrasound is done to detect conception? The most accurate method is transvaginal, but it is carried out only in the absence of contraindications.

Gestational age- one of the main components that a gynecologist needs to know about for proper management of pregnancy. After all, on the basis of this, the doctor will prescribe the necessary examinations, tests, routine ultrasounds, monitor intrauterine growth and development of the fetus, and identify possible violations during the course of the pregnancy. In addition, determining the due date allows you to fairly accurately calculate the date of birth and the date of maternity leave. It is necessary for the woman herself to know the duration of her pregnancy in order to mentally prepare for childbirth, have time to prepare a room or corner for the unborn baby, and purchase all the necessary accessories and clothes for him.

In this article we will look at how to determine the duration of pregnancy.

Calculate by monthly

For a woman who comes to register at the antenatal clinic, the gynecologist first of all asks a question about when her last period began. It is from this date that he begins to keep a record, despite the fact that fertilization has not yet occurred. It is known that fertilization of the egg occurs on the day of ovulation, which occurs in the middle of the menstrual cycle. This method of determining the gestational age is called “obstetric”.

An online calculator will help determine the period:

How to determine the gestational age by the date of conception

It is known that conception occurs only during ovulation within 24 hours after the egg leaves the follicle. And the viability of sperm in the female genital tract is up to 3 days. It turns out that the date of sexual intercourse does not always coincide with the date of conception.

Ovulation occurs in the middle of the menstrual cycle. A woman who monitors her menstrual cycle can quite accurately calculate the onset of ovulation. In addition, many at this time develop characteristic symptoms: aching pain in the lower abdomen, breast swelling, irritability, copious vaginal discharge, increased libido.

It is worth noting that only those women who have a regular menstrual cycle can determine the gestational age by the date of conception.

Online calculator:

(calculation will take a few seconds)

How to calculate using ultrasound

It is possible to find out the gestational age using the results of an ultrasound examination (ultrasound). It is determined according to the size of the fetus. The first ultrasound of the expectant mother is performed at 12-14 weeks, but it is still impossible to determine the exact date, since the development of the fetus occurs individually in each woman. It is possible to find out the age of the fetus by ultrasound with an accuracy of one day only in the first weeks after conception.

Determination during examination by a gynecologist

A gynecologist can determine a woman's gestational age by the size of her uterus during a gynecological examination. At 5-6 weeks, the size of the uterus can be compared to a chicken egg, at 8 weeks - to a goose egg. Later, it will be more difficult to determine how many weeks a woman has based on the size of her uterus.

Find out the due date by the first fetal movement

In the first pregnancy, a woman begins to feel fetal movements at 20 weeks, in the second - at 18 weeks. But this method does not always allow one to determine the period, since some expectant mothers may feel the first movements of the fetus earlier or later than the indicated weeks - some, due to the structural features of the body, cannot feel the movements of the fetus, others confuse the work of the intestines (increased gas formation) with movements.

Determine by hCG

Human chorionic gonadotropin (hCG)- one of the most important indicators indicating the onset of pregnancy and its normal development. The hormone begins to be produced in the female body after implantation of the embryo into the wall of the uterus. The level of hCG in the blood allows you to find out the approximate age of the fetus. With multiple pregnancy, the level of the hormone in the blood increases in proportion to the number of fetuses.