Obstetric and real gestational age

As is known, in most cases, it is quite difficult for young girls to establish the exact date of conception. That is why in medical practice, when establishing the term of pregnancy, always based on the date of the onset of the last, preceding pregnancy of menstruation. With this calculation, the so-called "obstetrical" gestation period is established, which is slightly larger and different from the real one.

How is the calculation of obstetric pregnancy?

Many women who became pregnant for the first time do not know what obstetrical pregnancy means and how to define it. With the normal duration of the menstrual cycle (28 days), conception is possible by about 14 days. Because of the fact that the date of the last menstruation is used in the calculation, usually the obstetric and embryonic (real) periods of pregnancy do not coincide. The runaway between them is the same 2 weeks, and sometimes 3.

How to calculate embryonic (real) pregnancy?

In order for a pregnant woman to calculate the actual duration of pregnancy, it is necessary to know exactly the date of conception. If you can not install it, then modern reusable pregnancy tests can come to the rescue. At the heart of the design of such devices are electronic sensors, which allow you to accurately determine the duration of pregnancy. The error is small.

Much easier is the case when a woman accurately remembers the date of the last sexual encounter. In this case, it is necessary to calculate just how many days have passed since that moment. The received number of weeks will be the real term of pregnancy.

How correctly to independently calculate the duration of your pregnancy?

According to statistical data, the difference between real and obstetric terms in 2 weeks, is observed only in 20% of pregnant women. Another 20% of the gap between these two terms is less than 14 days. The majority, 45%, - the difference between 2 terms varies in the 2-3 weeks interval, and only 15% of pregnant women make more than 3 weeks.

If the average duration of the menstrual cycle in a woman is different from the standard 28 days, then fertilization does not occur on day 14, but a little earlier or later. Therefore, the embryonic period will be very different from that which the gynecologist will establish.

For example, if a woman's cycle lasts 35 days, conception can occur only for 21 days, and not as usual, for 14. Therefore, the embryonic gestation period for 1 week of delay will be 5 weeks. At the same time, if you count from the last menstruation, then it will be 6 weeks.

What can I do if I can not determine the time limit myself?

In the early stages of pregnancy, it is possible to determine the time period accurately only by analyzing the hCG . With its help, the approximate age of the fetus is determined. In this case, the calculation is carried out from the date of the alleged conception. More accurately allows you to set the term of ultrasound. In carrying out this study, the dimensions of the individual parts of the fetal body are taken into account, according to which the age of the fetus is determined. Based on the results of the performed ultrasound can be established as obstetric pregnancy, and embryonic.

When determining the duration of pregnancy, you can also take into account the duration of the cycle. After all, with a longer menstrual cycle, conception comes a little later, so the birth will occur later.

Thus, knowing the main differences between obstetric and embryonic gestation, women will share these two concepts, and not be surprised that the time set by the doctor-gynecologist is longer than her intended, which is calculated according to the date of conception.