As is known, in most cases, young girls are quite difficult to establish the exact date of conception. That is why in medical practice, when determining the duration of pregnancy, they always repelled from the date of the beginning of the last, preceding pregnancy menstruation. With this calculation, establish the so-called “obstetric” gestational age, which is slightly longer and differs from the real one.
How to calculate the obstetric period of pregnancy?
Many women who become pregnant for the first time do not know what obstetric gestation means and how to define it. With a normal duration of the menstrual cycle (28 days), conception is possible for about 14 days. Due to the fact that when calculating using the date of the last menstruation, usually obstetric and fetal (real) periods of pregnancy do not match. The gap between them is the same 2 weeks, and sometimes 3.
How to calculate the embryonic (real) gestational age?
In order for a pregnant woman to independently calculate the actual gestational age, it is necessary to know the exact date of conception. If it cannot be established, then modern reusable pregnancy tests may come to the rescue. At the heart of the design of such devices are electronic sensors to accurately determine the duration of pregnancy. The error is small.
The situation is much easier when a woman remembers the date of her last sexual contact. In this case, it is necessary to calculate only how many days have passed since that moment. The resulting number of weeks will be the real duration of pregnancy.
According to statistics, the difference between the real and obstetric period of 2 weeks is observed only in 20% of pregnant women. Another 20% difference between these 2 terms is less than 14 days. In the majority, 45%, the difference between 2 terms varies in the range of 2-3 weeks, and only in 15% of pregnant women is more than 3 weeks.
If the average length of the menstrual cycle in a woman differs from the standard 28 days, then fertilization does not occur on the 14th day, but a little earlier or later. Therefore, the embryonic period will differ sharply from the one set by the gynecologist.
For example, if a woman’s cycle lasts 35 days, then conception can occur only on day 21, and not as usual, on 14. Therefore, the embryonic gestation period at 1 week delay will be equal to 5 weeks. At the same time, if you count from the last menstruation, it will already be 6 weeks.
What to do if the deadline cannot be determined by yourself?
In the early stages of pregnancy, it is possible to determine the period accurately enough only with the help of the analysis on hCG. With it, set the approximate age of the fetus. In this case, the calculation is from the date of the alleged conception. More accurately allows you to set the time of ultrasound. When conducting this study takes into account the size of individual parts of the body of the fetus, which is determined by its age. According to the results of the ultrasound can be set as obstetric gestational period and embryonic.
When determining the duration of pregnancy, you can also consider the duration of the cycle. After all, with a longer menstrual cycle, conception occurs a little bit later, therefore, childbirth will take place later.
Thus, knowing the main differences between obstetric and embryonic gestation, women will share these two concepts, and it is not surprising that the period set by the gynecologist is longer than expected, which is calculated according to the conception date.