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Table for determining the duration of pregnancy. True pregnancy - what is it? According to measurements of the uterus

Each representative of the fair sex, having learned that she is in a position, seeks to calculate as quickly as possible exact date pregnancy. It can be calculated from it approximate date the birth of a 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?

The women who come to medical institution 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 term interesting position about 2 put on less than that the period that the doctor tells the pregnant woman. Minimum term determining pregnancy by this method - 2-3 weeks.

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

  • biparietal size, determined between temporal bones(BPR);
  • fronto-occipital size (LZR);
  • head circumference (OG);
  • abdominal circumference (OC);
  • thigh length (DLB);
  • diameter chest(DGRK), 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 in the process 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. For getting 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 date last menstrual period 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). How to determine the gestational age irregular cycle? In such cases approximate values won't fit.

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 copious 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 with this method it is not always possible to know the exact date. 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, average duration menstrual cycle and 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.

Answers

For the correct management of pregnancy, the gynecologist needs to know the gestational age of the woman. Based on these data will be assigned to the expectant mother necessary tests, ultrasound and examinations.

It is also important for a woman to know the term in order to mentally prepare for childbirth. According to the gestational age, you can accurately calculate the time of going on maternity leave and the preliminary date of birth (PDR).

Methods for determining the gestational age:

1. Obstetric method

Upon first admission to antenatal clinic the gynecologist will ask about the date of the last menstruation, the duration of the menstrual cycle and its regularity. These data will be needed to determine the duration of pregnancy by menstruation.

Due to the irregularity of the cycle and its duration, the date of conception in most women is difficult to determine. If a woman's cycle is regular and is 28 days, then ovulation and conception will be on the 14th day from menstruation.

AT obstetric practice use the Negele formula: subtract 3 months from the first day of the last menstruation and add 7 days.

We add 7 days - it turns out July 15 of the PDR. If a woman's cycle is 21-35 days, then the EDD will be plus or minus 6 days.

This method of determining pregnancy is called obstetric.

2. Embryonic method

Embryonic gestational age is calculated from the date of conception, which coincides with the date of ovulation. Conception occurs during ovulation after the release of the egg from the follicle within one day. In the female genital tract, the sperm can last about 3 days. Therefore, the date of conception may differ from the date when sexual intercourse was performed.

Women with regular menstrual cycles can accurately determine the due date by the date of conception.

The embryonic period may differ from the obstetric period by an average of two weeks.

3. Pregnancy by ultrasound

It is possible to determine the exact gestational age by ultrasound up to 12 weeks by the average inner diameter of the egg and the change in about gestational sac.

The size of the fetus according to ultrasound coincides with the obstetric period and has an error of one week.

Ultrasound helps to learn about the formation and development of the child. If the ultrasound term is less than obstetric, this does not mean that it is incorrectly determined.

The following reasons may prevent the correct formation of the fetus:

  • improper functioning of the placenta;
  • multiple pregnancy;
  • diseases of the expectant mother;
  • malnutrition;
  • bad habits;
  • chromosomal abnormalities in a child.

If the term according to ultrasound, on the contrary, is longer than obstetric, then this may indicate a large weight of the unborn baby.

The reasons for the large weight of the child may be:

  1. hereditary factors;
  2. Improper nutrition during pregnancy;
  3. Diabetes.

When conducting ultrasound later than 12 weeks there may be a discrepancy with the norms of the development of the child.

The determination of the gestational age must be carried out in aggregate: to know the date of the beginning of the last menstruation, to conduct an ultrasound scan, to know the date of conception and to examine the formation of the fetus.

Hello my dear readers! Today I am talking about those first exciting moments when a woman is convinced that she will soon be called a mother. Usually such confidence comes after the test shows two strips. The next question that a pregnant woman begins to worry about is when to expect a birth. little miracle. There are many ways, both purely medical and folk, tested on ourselves by our grandmothers. Now we will talk about how doctors determine the duration of pregnancy.

Probably not a single woman wants the expected day of her birth to be a complete surprise. Determining the gestational age maximum precision, you can timely monitor the development and growth of the baby, prevent the occurrence of pathologies, determine the time for maternity leave.

Although it is a common truth that pregnancy lasts 9 months, doctors use a different system for calculating the period. Every woman has a term prenatal development her baby could range from 37 to 42 weeks.

Do you know at what stage of pregnancy you yourself were born? If not, ask your mom. Great chance that your baby will be born around the same time. An interesting fact is that girls are more nimble and are often born at 38-39 weeks, while boys patiently “wait” for the due date.

Why are there different dates?

Before calculating the date of birth, you need to figure out what obstetric and true term pregnancy. The first question that doctors ask during the examination is the day the last menstruation began. Many women wonder why the doctor wrote down the pregnancy two weeks more.

The thing is that the obstetric period is calculated from the first day of the start critical days, although conception itself usually occurs two weeks after this date. Do not be surprised by this method of calculation, because the period of egg maturation begins immediately after the start of a new menstrual period. The gynecologist determines and records the period by weeks.

The true term of the "interesting position" is calculated from the day of ovulation. Usually, a woman's body is ready to conceive a new life in the middle of the menstrual cycle. With a standard cycle length of 28-36 days, ovulation, respectively, occurs on days 13-16. But ovulation is not menstruation, and it can not always be determined with 100% accuracy.

Although there are many ladies, especially those who passionately want a child, who are sensitive to their bodies and can, according to certain signs, set the cherished day to the exact day. During this period, vaginal discharge may increase and increase basal body temperature body.

In addition, ovulation can be determined by ultrasound. But for this you need to go to the study for several days in a row, which, you see, is not possible.

And we again remember the regular cycle. If it works like a clock, then ovulation can be calculated with an accuracy of 2-3 days. Then the average duration of pregnancy is added to this date, that is, 280 days. This will be the baby's likely birthday.

Although we must also take into account that the day of conception and the day of sexual intercourse may not coincide! Spermatozoa remain active for up to 5 days. For example, sexual intercourse occurred on the 11th day of the cycle, and ovulation and conception on the 12th or even 14th day.

Determining the term for a gynecological examination

I want to note right away that at the first signs of pregnancy, you should immediately go to the doctor. Why is it so important to do this?

  • you will verify your assumptions;
  • you will pass the necessary tests to find out if your baby is developing correctly;
  • you will be prompted and organize the daily routine;
  • you will know the most accurate gestational age.

If the first visit to the gynecologist takes place after the eighth week, it will be more difficult to determine the exact date. If you went to the doctor for early dates, (this is 3-4 weeks), then experienced specialist it will be easy to determine how long you are in position. On examination and questioning future mother The term can be determined in the following ways:

  1. three months are subtracted from the first day of menstruation and seven days are added, the resulting date will be the expected day of delivery;
  2. the term is determined by the size of the uterus (on the 4th week it is compared with a chicken egg, and on the 8th - with a medium-sized apple);
  3. determine the period will help the height of the bottom of the uterus, which is calculated by measuring the distance from the pubis to the top of the uterus;
  4. the swelling of the labia and the change in the color of the walls of the vagina to dark red or purple-cyanotic are important;
  5. there is a change in the shape of the ovary, which increases on one side due to the so-called corpus luteum.

Each of these methods has its drawbacks. The first gives accurate data only if the woman has a regular menstrual cycle. And if menstruation is intermittent, for example, with polycystic ovaries? Then this method will tell you little. The size of the uterus may show a longer period than it actually is (for example, in the presence of fibroids). The bottom of the uterus is higher than normal with narrow pelvis or multiple pregnancy.

How is the duration of an ultrasound determined?

What if required precise definition term or the woman does not remember the date of the beginning of the last menstruation? In that case, on help will come ultrasound procedure. Often, expectant mothers are wary of him, they worry that such a procedure will harm the child. There is not the slightest cause for concern, ultrasound is absolutely harmless at any time.

Usually, a planned ultrasound is not prescribed immediately, but at 12-16 weeks. In this case, it is not necessary to pin hopes on the exact determination of the term. If you want to know the most accurate age of intrauterine development of your baby, feel free to do an ultrasound at 5-6 weeks.

The term is set, taking into account its average internal diameter. At an early stage, ultrasound determines the period quite accurately, because all embryos are still about the same size.

Ultrasound in the second trimester determines the period by the circumference of the fetal head or the diameter of its chest. Also install:

  • distance between the temporal bones;
  • thigh length;
  • circumference of the abdomen;
  • fronto-occipital size.

Reliable information is provided by the sizes of the femoral and humerus child. At the same time, the height and physique of the parents are taken into account. But very often the period determined by ultrasound may differ by 1-2 weeks from what is written in the card. Data on the size of the fetus depends on individual features child.

How to determine the duration of hCG

HCG is a unique hormone that is produced exclusively by pregnant women. Its very presence in the blood and urine already indicates that the mystery of the birth of a new life has come to pass. Pregnancy tests, which are sold in ordinary pharmacies, are based on the hCG hormone.

The production of hCG begins almost immediately after the introduction of the embryo into the uterus, and to detect it in enough can be already on the 6th day after conception. In the future, its level rises rapidly up to the 8th week.

During this period, it doubles every 2-3 days, on the basis of which the gestational age is determined. After the 9th week hCG level begins to gradually decrease and ceases to serve as a guideline.

I want to note that the term in terms of the level of hCG always differs from the obstetric one, since the first takes into account the date of conception, and the second - the first day of the onset of menstruation. By the way, there are exceptions here too. During pregnancy with twins, the level of hCG is also twice as high as normal.

If the hCG level is too low compared to the obstetric period, this can be an alarming sign. It is likely that it has come ectopic pregnancy or there was a fading of the fetus.

Determining the term by fetal movement

What could be more pleasant for a young mother than the “fuss” of a baby heard in her tummy for the first time? How long can you hear it? At first, his movements are so weak that they can only be recognized by listening carefully. Gradually, they intensify so much that they can even wake up mom at night. But this moment is still far away, the first fetal movement occurs at 18-20 weeks.

The first activity is noticed by ultrasound as early as the 8th week, but the child is still too small for the mother to catch these movements. Normally, during the first pregnancy, a woman feels stirring exactly at half the term - that is, at the 20th week, and with all subsequent ones a little earlier - at the 18th.

Therefore, the day when the baby first declares itself must be remembered and reported to your doctor. More greater value the fact of the movement of the child is when a woman does not remember the day the last menstruation began.

It is not uncommon for a nursing mother to become pregnant before the onset of menstruation and for the first months she does not even know about her situation. In this case, the first activity of the child will become the main guideline for doctors to determine the term.

Determining the date of birth by the first movement is enough reliable way, although some mothers may mistake the different activity of their intestines for the baby's pushes.

In late pregnancy, the activity of the baby decreases. Many mothers are very worried about this. Of course, it is necessary to tell the doctor about your feelings, but in most cases he will calm you down. The child is already large enough, he is cramped in his mother's stomach. Rare fetal tremors also serve as a signal that no more than a month is left before delivery.

How is it, you ask, it turns out that there is no way to determine the gestational age to the nearest day? Is it really necessary to know the exact day and hour? Knowing the approximate date, you will have time to fully prepare for such a responsible day, and the child can give a little surprise!

It was a pleasure to talk with you again! See you soon!

Discovering what has come long-awaited pregnancy, many women experience a surge of enthusiasm and at the same time a desire to learn as much as possible about their new condition. Since changes in the body of a woman who is expecting a child occur constantly, it is very convenient to calculate the weekly pregnancy calendar and monitor your condition by referring to it.

Calculate pregnancy calendar and gestational age

To calculate the pregnancy calendar and due date, special online services have been created. Using our calendar is simple: just enter the date when the last menstruation began in a special window - and in a few seconds you will become the owner of a personal calendar. The calculator will divide the duration of your pregnancy into weeks, indicating the time frame for each of them: the start date and end date of all weeks of your pregnancy separately.

This is very convenient and useful: referring to the personal calendar, you can adjust your lifestyle and nutrition, taking into account the needs of the body of the mother and child for different terms. You will also know in which of the periods the laying and development of the organs of your crumbs takes place, your own condition and well-being change, and this will make it easier for the doctor to monitor the well-being of your pregnancy. In addition, with the help of this calendar, it is easy to figure out when one trimester of pregnancy ends and another begins.

Calculate pregnancy calendar and due date

This pregnancy calendar also allows you to calculate the approximate due date. It falls on the end date of the fortieth week of pregnancy.

Of course, absolute - up to a day - accuracy with this and any other method of calculation cannot be obtained, because the duration of the menstrual cycle in different women may fluctuate, and the duration of the childbearing period is an absolutely individual indicator, despite the fact that there are average norms.

In any case, by calculating the weekly pregnancy calendar, you can find out what has changed in your body and what happens to your baby in one week or another, as well as when you can approximately prepare for childbirth and expect the birth of the most beloved creature in the world. !

In the first months intrauterine life embryonic development occurs at a rapid pace. Almost every week there is a laying and development of internal and external bodies and systems. future baby proportionately increases in size and weight. As he grows, his needs for certain chemical elements change, and a pregnant woman is prescribed folic acid, iodine preparations and certain diets. That is why for pregnancy management it is necessary to know its exact term. How to determine the gestational age?

Determining the duration of pregnancy by menstruation

Since menstruation stops with the onset of pregnancy, the date of the last discharge is the most common argument of obstetricians. obstetric term calculated from the first day of the last menstrual period and usually precedes real term pregnancy for 14 days, since ovulation occurs not at the beginning, but in the middle of the menstrual cycle. The method of determining the duration of pregnancy by menstruation is used to calculate the date of birth. For this, the date of the beginning of the last cycle is taken, three months are subtracted from it, then one week is added. This date, in turn, is necessary for calculating the timing maternity leave. However, in rare cases, after conception, spotting periods may occur, and this can seriously affect the result.

When calculating the gestational age, the moment of the first movement of the fetus, which occurs at week 20 in primiparas and at week 18 in the second and subsequent births, can also be taken into account. But this factor is very subjective, because some mothers do not immediately notice the movements, and some, on the contrary, take 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 determine the gestational age with an accuracy of up to a week by examining the vagina. To do this, the doctor performs palpation and evaluates the size of the uterus. At 4 weeks, it reaches a diameter chicken egg, at 8 weeks - goose. After 8 weeks, the size of the uterus in different women at the same gestational age may vary. Moreover, if the pregnancy is multiple, then the uterus increases 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 the gestational age by 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 a period of 36-38 weeks, ultrasound can determine the gestational age only with an accuracy of 1-2 weeks. How to determine the gestational age by ultrasound in the first trimester? The fact is that ultrasound is an accurate method, but not absolutely perfect. 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 fetal egg, and if you try to take a picture of the uterine cavity, you can barely make out a small dot. However, at such an early stage, the device does not always detect the presence of an embryo. It is much more likely to see the unborn child on an ultrasound and estimate 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 routine screening, a exact date conception you do not know? How to determine the gestational age by ultrasound in this case? In the second trimester, the main indicator is the size of the average inner diameter of the fetal egg, or the coccyx-parietal size of the embryo. These data allow you to determine the gestational age with an accuracy of 6 days. In the third trimester, the size of the cerebellum is taken as the main indicator of fetal development.

How to determine the duration of pregnancy by hCG

HCG is an abbreviation that stands for chorionic gonadotropin person. HCG is a hormone that begins to be produced after the implantation of the embryo into the uterine wall. How to determine the duration of pregnancy by hCG? The production of the hormone begins 6-8 days after the fertilization of the egg and increases over time. It is for the presence of hCG in the blood and urine that popular pharmacy tests for pregnancy - both paper and electronic. HCG hormone necessary to maintain 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 rate begins to gradually decrease. With multiple pregnancy, the level of the hormone increases in proportion to the number of fetuses, for example, with two fetuses - twice. Determining the gestational age by hCG will help when the ultrasound machine is not always able to see the fetus, but only if the embryo is not 5 weeks old.

Clearblue with gestational age

Modern pregnancy tests allow you not only to find out if your cherished 9 months have started, but also to determine how long you are. And one of these tests is Clearblue with the determination of the gestational age.

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

Clearblue with the determination of the duration of pregnancy is relevant already 4 days before the expected delay. Unlike strip tests, Clearblue gives an unambiguous and clear answer that will be visible on the screen within 24 hours.

Each of the methods we have given for determining the gestational age is effective at its stage. For example, in the very early stages, these are Clearblue and hCG tests. For a period of 5-8 weeks is obstetric method determine the size of the uterus. For a period of 8 weeks and beyond, the most reliable method is ultrasound.