The most frequently asked questions of expectant mothers concern the timing of pregnancy and childbirth. Some women know for sure the date of conception and begin to keep a report from it, but when registering with an antenatal clinic, the doctor determines the period by the size of the uterus and the results of an ultrasound scan, and later - by the first movements of the fetus. However, it may not coincide with what was indicated by the pregnant woman.
On average, pregnancy lasts 40 weeks, which equals 28 obstetric months (28 days duration), or 280 days. In reality, these terms fit into 9 calendar months, plus seven days. Therefore, it is customary to talk about 9 months of pregnancy. The birth of a baby at 38-42 weeks is considered normal if there are no signs indicating the immaturity or overmaturity of the baby. If the child was born later than this period, then the pregnancy is considered post-term, otherwise it is premature.
Obstetricians-gynecologists begin the countdown of pregnancy from the first day of the last menstruation. Usually, the actual period is 13-16 days less, since conception occurs approximately in the middle of the menstrual cycle, i.e. at the time of ovulation. However, to avoid confusion, doctors start counting pregnancy 2 weeks earlier than conception.
If you do not know the exact date of conception, then it is most correct to count the weeks of pregnancy based on the results of an ultrasound scan. Routine research is carried out at 12-13 weeks of pregnancy. As a rule, it coincides with the period set at the first appointment with the gynecologist. But, if there are discrepancies, then it is better to focus on the term set with the help of ultrasound.
In some cases, there may be a discrepancy between the size of the fetus and the gestational age. For example, as a result of polyhydramnios, the presence of tumors, etc. These data are taken into account by specialists in the study. In this case, the number of weeks of pregnancy is set, calculated from the first day of the last menstruation, and with the help of ultrasound at a later date, it is corrected.