From what day does the countdown begin?

In this article we will tell you when the countdown begins to take pregnancy according to the rules of gynecology.

Content

Often in women, pregnancy with obstetric data does not coincide. And all because the countdown of pregnancy starts from different dates. Let's find out how to correctly calculate the date of pregnancy, and also tell you why this order.

From what day does the countdown begin: the obstetric method of calculation

The countdown begins with the first day of the last menstruation!

This is the obstetric method. Although it is very averaged, and the real term is ahead of average by 14 days, nevertheless in gynecology it has been used for more than one century and is considered in comparison the most accurate method. After all, almost every girl knows the beginning of menstruation (at least approximate), but it is difficult to guess the exact day of direct conception. The total gestational age according to obstetric data is 40 weeks. But childbirth can be from 38 to 42 weeks, depending on the characteristics of the mother’s body and the development of the baby.

To calculate the approximate date of childbirth, the formula of Negel is used:

To the first menstrual day we add 9 months and 7 days.

But there are simplified methods of calculation on the same principle:

Remove 3 months and add 7 days;
You can count 280 days, which is considered an average value and equal to 10 obstetric months (in them exactly 4 weeks).

Important: if your cycle lasts longer than 32 days, then childbirth will be more after 40 weeks. The large fruit is also carried longer. But with multiple pregnancy, childbirth will occur earlier, as in the case of a 28-day cycle.

Breakfast count on the Day of Conception: embryonic method

According to statistics, ovulation occurs approximately 14 days before the start of the next menstruation, Provided 28-day cycle. But the cycle is more or less, and stress, medication, fatigue, weight, chronic diseases or even a cold can affect the process itself.
- If you have Regular cycle without failures, then you can independently calculate the date of ovulation at basal temperature.
- With an irregular cycle ovulation can fall on 5, 19 or even 28 days. It is very difficult to set the exact date yourself. But you can calculate it according to your well -being and symptoms of the body. Read more about this in the article "What is ovulation and what are its signs?", as well as "What should be the discharge during ovulation?"
It is also worth considering the fact that sperm in the female body can maintain their life up to 5 days. And conception can occur a little later than the ovulation itself. But no later than 24-48 hours, T.K. For about this period, an unfertilized egg located in the phallopian tube dies.

The embryonic countdown of pregnancy from the obstetric period in 65% “lags behind” by about 2-3 weeks, in 20% of women this difference is less than 14 days and only in 15% this difference exceeds 3 weeks. In this case, the obstetric period is adjusted.

The countdown on ultrasound: with what period do the data coincide - obstetric or embryonic?

The most reliable method of determining the exact deadline is an ultrasound.

What the embryo looks like by day until 23 weeks

Ultrasound for the definition of the "age" of the fetus is done up to 12 weeks! It is before this period that the embryos develop almost equally, and in its length (coccyge-dark size-KTR) and the inner diameter of the fetal egg determine the term.
- After the individual and genetic development of the fetus comes into force, so different women with one gestational age will not coincide the “age” of the embryo.
- And after 22 weeks, they evaluate the development of the baby, the presence/absence of pathologies, etc.
In the first trimester, the results are compared with the embryonic period, Therefore, by ultrasound, it is also about 2 weeks less. But in the devices, data are automatically adjusted to the obstetric countdown in pregnancy so that there is no confusion.
- In cases of a strong difference (more than 3 weeks), the gestational age is already adjusted according to the ultrasound. But if this difference is several days, then they do not make adjustment. This happens when ovulation was at the end of the cycle.
In the late stages of tables with results are calculated according to obstetric data (i.e. from the last menstruation). Since the difference in readings may vary greatly, both in the larger and lower side. Especially in the third trimester, where genetics and individual development of the baby play a large role.

Other pregnancy methods

HCG level indicator in the blood Used as an additional method of reference pregnancy. At different times, the concentration of the hormone changes. Example:

You can determine the approximate period In the height of the bottom of the uterus (VSDM). If until 15-16 weeks it is felt below the navel, then after 24-25 it rises almost to its level. Although the accuracy of the data is affected by the number of embryos, amniotic fluid and the structure of the pelvis of the woman in labor.
- Also an experienced gynecologist in size of the uterus Set the approximate period. For example, for 4-5 weeks of pregnancy, the uterus is the size of a chicken egg, and on 8-like a goose.
Very rarely, the gestational age is set or adjusted By the date of the fetal move. To do it is even erroneous! Indeed, in primary women, the first rumors are felt by/after 20 weeks, and in multiparous-it is possible even for 16-17 weeks. But all this is very individual, where the weight and physique of the woman in labor, the kind of activity, the way of life, the development of the baby and the emotional connection with him plays the role.
For artificial fertilization (IVF), a gestational period is used pregnancy, which coincides with the embryonic period for exactly up to a minute. After all, the countdown begins from the moment of the merger of the sex cells of the mother and father.
There are today calendars and counters, To calculate the term of conception according to the introduced individual data. On them you can also determine the date of birth, the weight of the baby or the floor. But do not overestimate their accuracy, because all the data is too averaged.

Why is the countdown is carried out by weeks, and not for months?

Exclusively because of convenience! The kid is developing very quickly and actively, so Changes are noticeable and important for every week, Especially in the first trimester. That is why doctors conduct pregnancy for a week. The trimester means a period of 13 weeks (3 months and 1 day):