There are different reasons for stomach pain during pregnancy depending on the pregnancy period: 1. irregular vague abdominal pain in early pregnancy is mostly considered to be a physiological phenomenon caused by the enlargement of the uterus and pelvic congestion; 2. vague pain after 8 weeks of pregnancy is mostly considered to be caused by irregular uterine contractions or abdominal pain caused by the pulling of the round ligaments on both sides of the uterus; 3. If severe abdominal pain occurs in early pregnancy, the possibility of ectopic pregnancy or miscarriage should be highly suspected; 4. The symptoms of vague pain in the middle and late pregnancy, which can be relieved after rest, are usually caused by irregular uterine contractions. It can be triggered by stimulation of sexual life, strenuous exercise, physical labor, etc.; 5. Abdominal pain that appears at full term is a kind of a precursor of labor. When the pain symptom further intensifies, lengthens in duration and shortens in interval, it is a manifestation of labor.