Why is it important to know the gestational age?
The first thing a doctor does at the appointment of a pregnant woman is to set the date of birth. Knowing the timing of pregnancy is very important for many reasons, and not only so that a woman can independently prepare for childbirth. This is also the main criterion on the basis of which the correct development of the baby in the womb is determined. The doctor prescribes tests, examinations, monitors the intrauterine development of the baby. Knowing the main stages of the correct development of the child, comparing with them the results of studies at a certain time, doctors can correct minor discrepancies. In addition, the determination of the gestational age is also necessary for registration of maternity leave documentation. Under the law, a woman can go on maternity leave after reaching 30 weeks of pregnancy.
Thus, the exact date of birth is an important point. With the use of modern equipment, today it can be calculated with an accuracy of one day. Laboratory studies are carried out on strictly defined days. For the woman herself and her family there is also a psychological moment. On the one hand, you need to buy household items and clothes for the baby, on the other, it is important to maintain the health of the baby, since premature and belated delivery can be difficult.
Date of birth for the last menstruation (Negele formula)
Pregnancy lasts about 10 lunar months (40 weeks or 280 days). Doctors distinguish between obstetric and real (true) pregnancy. The easiest way to count the time from the exact parameter, since the date of ovulation can vary. Obstetricians take into account the date of the last menstruation (usually 1-1, 5 days), from this moment the egg begins its development and maturation, in the future the sperm fertilizes it. The obstetric calculation allows you to determine the date of birth by a simple formula - from the first day of the last menstruation you need to subtract 3 months and add seven days.
Date of birth by ovulation
So nature ordered that the conception of a child can only occur during ovulation, when a mature egg leaves the ovary in order to “wait” for the sperm in the fallopian tubes. If sexual intercourse takes place and the meeting occurs, the probability of conception is very high. Ovulation lasts about a day, by this date and the timing of future births is determined. Sometimes the ovaries rest, and ovulation in the body of a woman does not occur. In a young healthy woman, this can happen about 1-3 times a year, in older women there are more such months. True and obstetric gestation periods differ by approximately two weeks. With a menstrual cycle of 28 days, ovulation occurs on day 14, if the number of days in the cycle is different, then the time of ovulation is shifted. Hence, some discrepancies in the timing of pregnancy by the date of ovulation.
How to determine ovulation? For this, special tests have been developed that can be purchased at any pharmacy. Another way is regular changes in basal temperature. In the first half, its values will be below 37 degrees, then it decreases (the day before ovulation). If the temperature rose above 37 degrees, and there are no diseases - we can assume with a high degree of probability that this is the day of ovulation. Thus, the gestation period begins when the temperature rises above 37 degrees.
Some women determine this day by listening to their bodies. These may be some distinctive symptoms - a characteristic pain in the lower abdomen and specific discharge appear, sexual desire increases. This sensitivity helps them more accurately determine the date of birth for themselves.
Determining the date of pregnancy by ultrasound
But the most accurate way is still considered an ultrasound. This is the only way to know for sure that ovulation occurred on that day. To do this, I would have to go for an ultrasound scan for several days in a row, which is inconvenient both financially and physically, and is it worth it to spend time just because of the date? Moreover, it is worth suffering only a little, and the date of birth can be determined much more accurately. Diagnostic ultrasound is carried out at 12,20,32 weeks, but to determine the date of birth more reliably is possible only at the initial stages of pregnancy.
The fact is that up to 6-7 weeks, embryos grow proportionally, and their sizes are almost the same. The longer the term, the more they differ in size and type. The appearance will be of the parents' appearance, mass, height, and so on. Why is it important to get an ultrasound in early pregnancy? The accuracy of the method relative to the date of birth after 8-12 weeks is reduced due to the different development of children. Doctors may make a mistake and make a diagnosis of "Intrauterine growth retardation", which can injure a future woman in labor. Most often this happens with women who are light in weight.
Determination of gestational age during gynecological examination
For the same reason, examination of a gynecologist in the first weeks of pregnancy can give more information about the estimated date of birth, since the uterus increases in a certain order. Experienced gynecologists determine the time of birth during a vaginal examination with an accuracy of one day, but only up to about 7-8 weeks. For example, at 4 weeks the uterus resembles a chicken egg in size, and at 8 weeks it already has a goose. About the second trimester, the size of the fetus in different women at the same time is different, therefore, the data of the vaginal examination cannot be as accurate as in the first weeks.
The first stir - how to determine the gestational age
A woman who is pregnant for the first time, as a rule, feels the baby is moving at 20 weeks. Multiparous women hear this even earlier - at 18 weeks. Be sure to tell the gynecologist the date of the first stirring - it is recorded on the card and is of great importance in determining the duration of pregnancy and the date of birth. By the date of the first stirring, 4.5 months for a primiparous woman and 5 months (18 weeks) for multiparous women are added. This method is only supportive, as some women, especially thin ones, can feel movements earlier or later than usual. But many doctors believe that it is impossible to feel the child ahead of time. Women take the movement of gas in the intestines as a stir, because many have increased gas formation during pregnancy.
Determination of gestational age by measuring the length of the uterus and fetus.
A more complex way of calculating the gestational age is to measure the size of the uterus. Most accurately, a gynecologist will do it. The bladder should be empty to exclude measurement errors. Lying on a couch, a woman should straighten her legs. A centimeter tape or tazomer measures the length of the uterus. It is believed that it equals the number of weeks. Example: the length of the uterus is 35 cm, which means a gestational age of 35 weeks.
Thus, having several methods in their arsenal, doctors can most accurately determine the date of birth. Sometimes there are discrepancies in different ways, but they are minimal - no more than a week. For the development of pregnancy, this is not essential. And not always the birth of a child coincides with the date set by the doctors. Much depends on the gestational development of the fetus, as well as the genetic characteristics of the parents. If childbirth occurs plus or minus a few days from the due date, there is no cause for concern.
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