How to accurately calculate the duration of pregnancy in weeks?

Women who have an active sex life do not always remember the date of the last sexual intercourse. That's why there are difficulties in calculating the period of pregnancy. Let's take a closer look at the calculation algorithm and find out how to accurately calculate the length of pregnancy in weeks and why there are several methods of calculation.

What is an "embryonic period" and how is it calculated?

As already mentioned above, women often find it difficult to name the date of the last sex. It is from the time of fertilization that the so-called embryonic gestation period is calculated. In practice, it is rarely used. In most cases, it is possible to establish it only by carrying out an ultrasound.

So, during such a survey the doctor makes a measurement of the size of the fetus, according to which the gestational period itself is established . However, even in this case, inaccuracies in the calculations are possible, because each organism has its own individual developmental features.

Often, when determining the embryonic period, doctors rely on the date of ovulation. But in such cases errors in calculations are possible. The thing is that ovulation itself is subject to external factors, so in some menstrual cycles it may be noted early, or, on the contrary, later onset.

If we talk about how to correctly calculate the embryonic period of pregnancy by weeks, then for this from the current date the woman needs to take away the number of weeks that passed from the prospective day of fertilization (the day when there was sex). With such calculations, the duration of the entire pregnancy should be 266 days, which is equal to 38 calendar weeks.

How can I count the number of weeks of pregnancy and the period of birth?

Despite the fact that embryonic gestation is more accurate and directly reflects the development of the fetus, all physicians use midwifery when calculating. At the same time, the physicians start counting the gestational period from the first day of the last menstruation. So, the obstetrical period is equal to the number of weeks that have elapsed from the above date to the present day.

To determine the date of birth, you can use the so-called formula of Nehiel. So, from the first day of the last, noted at a woman's menstruation, it is necessary to take 3 months. After this, the week is added to the received date, or 7 days. As a result, a pregnant woman can establish the expected date of the baby's appearance.

What other methods exist for determining gestational age?

The methods described above for determining the duration of the current pregnancy are the main ones. This is explained by the fact that no additional devices or apparatus are required for their use. However, in order to confirm the accuracy of the calculation, when performing ultrasound, physicians often perform measurements of the fetal body itself.

Also, at later dates, it is possible to use such a method as setting a time limit for the first perturbation. It is generally believed that the first "communication" with the baby is observed for women who are pregnant with the first-born child at the time of 20 weeks. As for the re-breeding, as a rule, in such women, the first movements can be observed 2 weeks earlier.

Thus, as can be seen from the article, it is possible to calculate the exact length of pregnancy by weeks in several ways. However, when using them, it is worth considering the fact that none of them is perfect for various reasons. Proof of this can serve, so-called "early" or, on the contrary, "late" birth, when delivery takes place on time, but the time of its beginning does not coincide with the date established by calculation.