The normal gestation period is about 40 weeks, with some individual variation. Calculation of gestational weeks is usually counted from the first day of the last menstrual period, with 7 days being 1 week. The entire gestational period is about 280 days, or 10 gestational months and 40 gestational weeks. It is generally divided into three stages; early pregnancy is defined as 13⁺⁶ weeks, mid-pregnancy is 14 weeks-27⁺⁶ weeks, and late pregnancy is 28 weeks and beyond. A pregnancy of 28 weeks or less is called preterm labor. At this time, the fetus is not yet fully developed, but it is already viable after birth, and the survival rate is getting higher as medical conditions improve. Full 37 weeks belongs to the full-term, at this time the fetus is already well developed, full-term pregnancy at any time after the pregnancy may be initiated, do not have to wait until the 40th week of pregnancy to delivery. During pregnancy, pregnant women must complete the relevant examinations and undergo regular obstetric checkups.