Usually births between 37 and 42 weeks of pregnancy are normal full-term births. Pregnancy is a gradual process. In the early and middle stages of pregnancy, the uterus is in a resting state, which also ensures that the uterus can tolerate the load of the fetus and appendages. As the fetus grows, the pressure in the uterine cavity increases in the late stages of pregnancy, the fetus grows slowly and the oxygen and nutrients needed in the later stages increase, but the placenta, which supplies nutrients to the fetus, is relatively undersupplied at this time; in the early stages of labor, the pre-disclosed part of the fetus presses on the lower part of the uterus and the cervical opening, which causes contractions, water breakage and labor due to a combination of internal regulation. The labor situation varies from person to person, as some people experience redness first and then contractions. Some people experience contractions directly, so it is important for pregnant women to be more observant. Of course, there are not only normal full-term births, but also premature and overdue births. This is why regular checkups are especially important during pregnancy and should be taken seriously. During normal perinatal checkups, the doctor will estimate the approximate date of delivery based on the actual number of weeks of pregnancy and the size of the fetus.