The number of months a woman is pregnant before she can give birth is calculated from the obstetrical point of view, according to 4 weeks a month, the duration of pregnancy is 40 weeks, which is exactly 10 months. The real duration of pregnancy is not 10 months, but about 280 days, or 9 months and a week. Of course, not all women give birth at exactly one week over 9 months, but it is normal to give birth two weeks earlier or later than the due date. Since it is difficult for every woman to determine the exact time of conception, obstetrics has established that the first day of the last menstrual period is used to calculate the expected date of delivery, which is 280 days for the entire pregnancy and 10 gestational months. In general, a woman will give birth to her baby within 38 to 42 weeks of pregnancy. Therefore, it is important to be ready for delivery after the 37th week of pregnancy to prevent emergencies. If there are no signs of labor by 41 weeks of pregnancy, you should go to the hospital in time to have relevant aspects checked to prevent adverse conditions such as aging placenta and low amniotic fluid. If a woman cannot remember her last menstrual period, she can also go to the hospital at this stage for an ultrasound examination of the fetus to measure the biparietal diameter, femur length and other data to estimate the expected date of delivery. It is important for women to take care of their nutrition and rest throughout their pregnancy, and to be sure to have their Down’s syndrome screening and 4D ultrasound examinations on time.