What is embryonic gestation?
Under this term in obstetrics, it is customary to understand the number of weeks that have passed since the moment of fertilization. In other words, the countdown begins immediately from the day on which the sexual act was performed.
This parameter is the most objective; reflects completely all the temporary stages of embryo development. However, it is used quite rarely. The main reason for its low prevalence is the fact that quite often a woman can not accurately name the estimated date of conception, in view of the fact that most young women have an active sexual life.
In the same cases, when the expectant mother accurately remembers such a date as the day of sex, she can easily find out what period of pregnancy she has now and calculate it by weeks. To do this, it is sufficient, from the current date, to count the number of days that have passed since the last sexual intercourse. The result should be divided into 7, and the result is the number of full gestational weeks.
What is obstetric pregnancy?
This method of calculating the duration of gestation is the most common. They are used almost every time when setting the term of the doctor.
The starting point for such calculations is the first day of the last menstruation. In order to establish this way, it is necessary to calculate how many days have passed since the above-mentioned moment. The result will be the obstetric term.
It should be noted that the obstetric term is always more embryonic. The fact is that when it is established, the time interval before ovulation is taken into account. That is why, in most cases, the difference between obstetric and embryonic gestation is 2 weeks. So, in calculating the duration of the entire pregnancy, midwives believe that it lasts 40 weeks (38 weeks with an embryonic period).
How can I set the time when a baby is born?
Progress does not stand still, and today for the convenience of women there is a so-called pregnancy calendar, which allows you to calculate for weeks not only the gestation period, but the date of birth. Moreover, today a woman can do it right online. It is enough to enter the date of the first day of the last monthly, the current date, and in the end you can get the estimated day of the baby's appearance.
Also, the calculation of the termination of pregnancy (delivery) is carried out with the help of an ordinary calendar, both for weeks and by days. For the speed and ease of calculations, obstetricians use the so-called Negele formula.
So, for this it is enough to add 7 days to the very first day of the last woman's menstruation, after which to subtract 3 months. The date is the expected day of childbirth. With such calculations, the gestation period is 280 days.
Thus, as can be seen from the article, it is possible to establish the terms of pregnancy for weeks and months quite simply, knowing only the exact date of the first day of the last month, or the day of the very conception itself. To confirm their calculations, doctors perform ultrasound, which makes measurements of individual parts of the body of the baby, comparing them with tabulated values.