For the calculation of weeks of pregnancy, it is usually counted week by week, according to the 1st day of the last menstrual period. The days, weeks and months of pregnancy are calculated from the first day of the last menstrual period. The due date is also calculated from the 1st day of the last menstrual period, with the month -3 or +9 and the date +7. For example, if you have your menstrual period on January 1, you may have intercourse and conceive in mid-January, then the later weeks of pregnancy will be calculated from January 1 to February 1, which represents 4 weeks and 3 days of pregnancy, and the later weeks of pregnancy will also be calculated accordingly. The expected date of delivery is October 8th. This method is more accurate for women who have a regular menstrual cycle, but if the menstrual cycle is irregular, it is necessary to combine it with ultrasound to calculate the gestational week. If there is a big difference between the week of pregnancy determined by ultrasound and the week of pregnancy calculated according to the last menstrual period, the week of pregnancy determined by ultrasound should prevail. Pregnant women can also estimate the week of pregnancy through conscious fetal movement, such as first-time mothers conscious fetal movement time is about 18-20 weeks, but this method is too rough. For early pregnancy pregnant women need to pay attention to a balanced diet, pay attention to rest, do not overwork, do not have sex in early pregnancy, etc., in order to reduce the chances of miscarriage in early pregnancy.