The belly is not necessarily big in the fourth month of pregnancy, and there are individual differences. With the increase of pregnancy weeks, the uterus will gradually increase in the fourth month of pregnancy that is 16 weeks of pregnancy uterine bottom up to the umbilical cord between the shame, at this time the pregnant woman’s stomach can be shown to be slightly bulging, thin pregnant women can be seen from the appearance of the stomach is slightly larger, but for the obese pregnant women, at this time, the abdominal bulging is not obvious, the stomach is not big, from the appearance of the pregnant woman can not be recognized. After the middle of pregnancy, the height of the uterine fundus should be measured during each checkup to check the week of pregnancy. The height of the uterine fundus varies depending on the development of the fetus, the number of fetuses and the amount of amniotic fluid. Under normal circumstances, the height of the uterine fundus is highest at 36 weeks of gestation, reaching 2 transverse fingers below the xiphoid process, and may decrease slightly after full term as the prenatal presentation enters the pelvis. Abnormalities should be actively diagnosed and treated.