Under normal circumstances, pregnancy lasts 280 days. If menstruation is regular, the 280th day of pregnancy is the expected date of delivery, counting from the first day of the last menstrual period. A regular menstrual cycle usually lasts about 30 days, and it is normal for most pregnant women to go into labor two weeks before and two weeks after their due date. It is important to note that the due date is only an indication that labor is imminent at that number of weeks, and is not a fixed period of time for delivery. If you have irregular periods, delayed or early menstruation, short or long periods, etc., you need to calculate the gestational week according to the ultrasound of early pregnancy and further estimate the expected date of labor, and take the estimated gestational week as the basis for regular obstetric checkups in order to ensure the healthy delivery of the fetus. During pregnancy, it is necessary to maintain a happy mood, avoid staying up late, and ensure sufficient rest and sleep; pay attention to balanced nutrition, avoid partiality or picky eating, and timely supplementation of micronutrients, which is conducive to the growth and development of the fetus.