Pregnancy to delivery goes through about 40 weeks, 280 days and 10 gestational months. The time experienced by pregnancy is not exactly the same because different women have different menstrual cycles, different menstrual periods, different times of ovulation, different times of egg fertilization after intercourse, and different development of the embryo in the uterine cavity. The due date is 280 days backward from the first day of the last menstrual period. Some pregnant women may give birth 1-2 weeks earlier, while others may push it back 1-2 weeks. It is normal to give birth after 37 weeks of pregnancy into 38 weeks and before 42 weeks of pregnancy, which means that the number of days of pregnancy fluctuates between 266 and 294 days.