The average menstrual cycle lasts 3-7 days, and the average menstrual cycle is 28 days. 7 days early or 7 days late is the normal range, and the volume of menstrual blood is about 20-120 ml. During menstruation, some women may experience abdominal pain, lumbago and breast swelling before or during menstruation. During menstruation, you should wash your vulva frequently, not with soap, so as not to cause infection in the vaginal environment.