How correctly to count weeks of pregnancy?

Often young women, being in a position, are wondering about how to correctly count the weeks of pregnancy, and how doctors do it. The main 2 methods that are used in the calculation are the calendar and instrumental - the use of the ultrasound machine.

Calendar methods for determining the duration of pregnancy

The most common way is calendar. To conduct it, no special equipment is required. The only thing a girl should know is the date of the last month. That is why, before you start to count the number of obstetric weeks of pregnancy, gynecologists ask a question about the date of the first day of the last menstruation. It is this number that is the starting point from which the countdown begins. In this case, the received number of weeks is usually called the "obstetric term" of pregnancy.

This method is less informative, because takes into account not the time from the moment of conception, but from the beginning of the cycle. As is known, this phenomenon is observed approximately in the middle of the cycle (13-14 days). As a result, the gestation period very often exceeds the real one for the very 2 weeks.

Much easier is the case when the girl knows exactly the date of conception. In such cases, the question of how to count how many weeks of pregnancy, is less common. At the same time, the date is taken as the origin of the count, when, according to the information of the woman, the fusion of male and female sex cells occurred. The number of weeks of pregnancy received as a result of this calculation was called the gestational age. Due to the fact that the girl does not always remember exactly the date of the last sexual intercourse, most often calculate the obstetric term.

Ultrasonic method for determining gestational age

At later dates of gestation, for timely diagnosis of developmental disorders, ultrasound is performed quite often. However, it can be used to determine pregnancy, as well as to determine its term.

The highest accuracy is provided by examinations with the help of this device, conducted up to 8 weeks. This is explained by the fact that until this point all the embryos develop the same way. That is why ultrasound allows you to set the time to within 1 day.

Thus, every woman should know how correctly gynecologists consider obstetric and gestational terms, in order to determine how many weeks of pregnancy has already passed by herself.