In addition to the health of the baby, the expectant mother also cares about the question of determining the period of pregnancy. This is necessary not only to establish an approximate date of delivery, but also to calculate the date of the beginning of maternity leave. The most commonly used method is to determine the duration of pregnancy for menstruation.
How are the last months and pregnancy related?
The first question of the obstetrician-gynecologist at the reception regarding pregnancy will concern the date of the onset of the last menstruation. In addition, the doctor is interested in the duration of the menstrual cycle, its regularity. It is these data that will be used to determine the duration of pregnancy on a monthly basis.
The fact is that in obstetrical practice it is customary to count the pregnancy from the first day of the last menstruation. This, in fact, the only landmark, since the date of conception in most cases is almost impossible to establish. Many adhere to the general formula of calculations, which is based on a 28-day regular cycle. In this case, ovulation and conception occur, as a rule, on the 14th day from the onset of menstruation. However, not every woman can boast of the regularity of her cycles, and their duration, according to statistics, for most ladies differs from the reference one in a larger or smaller direction. Therefore, the determination of the gestational age for the last month is not always reliable.
Obstetricians-gynecologists distinguish the actual obstetrical gestation period (from the first day of the last month's period) and embryonic, or true, gestation (from the date of ovulation and fertilization).
How to determine the duration of pregnancy on a monthly basis?
Calculate the length of pregnancy for a month you can and most. For this, in addition to the date of the onset of your last menstruation, you need to know the total duration of the pregnancy - 280 days, or 40 weeks. Thus, you can calculate the approximate date of birth, counting from the first day of the last monthly 40 weeks.
Doctors do it easier - they use the formula of Negele: add 9 months and 7 days to the date of the first day of the last menstruation or subtract 3 months and add to the received number 7. You can do this without calculation, using a special pregnancy calendar for the last month. In the red line we find the date of the beginning of the last menstruation, next to it, in the yellow line, we look at the date of the probable day of birth.
Do not believe me - double-check
However, determining the duration of pregnancy on a monthly basis is by no means the most reliable method. If a woman has an irregular menstrual cycle, then it is necessary to use other ways:
- to have an examination with a gynecologist;
- calculate by the date of the first stirring of the fetus;
- to undergo ultrasound examination.
At the beginning of pregnancy at a reception with an obstetrician-gynecologist you will undergo an examination on a gynecological chair. An experienced doctor will determine the duration of pregnancy by the size of the uterus, and at later dates - according to the size of the fetus and the height of the uterine fundus.
The date of the first stir fetus obstetricians-gynecologists believe is very important, because with her help you can calculate the estimated term of childbirth. For this, by the day of the first stirring, a certain number of weeks is added (for a pervious woman - 20 weeks, for a recurrent woman - 22 weeks).
The method of determining the duration of pregnancy using ultrasound (up to 12 weeks) is the most accurate: an experienced specialist will determine the true duration of pregnancy. However, whatever methods mankind used to penetrate into the mystery of the birth of a new life, the baby will be born in his time as soon as he is fully ready to meet the world.