The first menstruation in adolescent women is very easy to determine, when the patient’s age is between 11-15 years old, excluding trauma, vaginal bleeding should be considered as menstruation. Women’s menstruation is self-limiting, lasting 2-8 days, and the volume of menstruation is greater than 20 ml and less than 80 ml, which does not cause anemia. Women of childbearing age have a fixed menstrual cycle, and as long as the self-limiting vaginal bleeding occurs according to their own cycle, it is a normal menstruation. A woman’s menstrual cycle lasts between 21-35 days, and her menstrual period lasts between 2-8 days. Women of childbearing age who experience vaginal bleeding during their menstrual period should pay attention to the small amount of bleeding or other abnormalities, and must rule out the possibility of an abnormal pregnancy. When the patient has a preeclampsia or ectopic pregnancy, vaginal bleeding can occur during the menstrual period, as in menstruation, the amount and duration of bleeding is abnormal, the bleeding is small and lasts for a long time.