Babies generally take 40 weeks to be born, or 280 days, but there is a great deal of individual variation, as some babies may be born prematurely or delayed. A baby born at more than 37 weeks and less than 42 weeks is a normal full-term birth, but a baby born at less than 37 weeks is premature and a baby born at more than 42 weeks is overdue. Premature babies are prone to neonatal respiratory distress syndrome, which is mainly caused by poor lung development. Pregnancy is generally divided into early pregnancy, middle pregnancy and late pregnancy. Early pregnancy refers to the period before 12 weeks of gestation, which is prone to miscarriage, middle pregnancy is from 12 weeks to 28 weeks, and late pregnancy refers to the period after 28 weeks, which is prone to preterm birth. Therefore, early and late pregnancy requires special attention to prevent the possibility of pregnancy accidents, enhance nutritional intake, and regular prenatal checkups.