A pregnant belly is the first to bulge from the lower abdomen. A woman’s uterus is located in the pelvic cavity, in the early stages of pregnancy, the fetus is still relatively small, from the appearance of pregnancy can not be seen, by the end of the 12th week of pregnancy, the enlarged uterus beyond the pelvic cavity, the uterine floor to the pubic bone joint 2-3 horizontal finger position. By the end of the 16th week of pregnancy, the uterine fundus reaches the position between the navel and the pubic symphysis, and the lower abdominal bulge can already be seen from the outside. The size of the fetus and the week of pregnancy can be estimated by examining the enlarged uterus, measuring the height of the uterine fundus by hand or measuring the length of the uterus over the symphysis pubis by ruler. Ultrasound can also be performed to monitor fetal development and to check that the development is consistent with the gestational week. It is important to do a good maternity check during pregnancy. The growth and development of the fetus can be assessed through the maternity check, and if there are any abnormal indicators, it is important to consult a doctor for checkups in a timely manner.