It is forbidden to have intercourse during menstruation. First of all, because the entire pelvic cavity is in a state of congestion, intercourse can easily cause heavy bleeding and prolong the period. Secondly, the opening of the cervix is open and bacteria can easily travel up the vagina to the cervical opening and infect the uterine cavity or even the entire pelvis, causing a series of gynecological inflammatory diseases, such as endometritis, adnexitis, pelvic inflammatory disease, etc. Patients may experience abdominal pain, lumbar pain, falling, and in severe cases, fever and other symptoms. Therefore, in clinical practice, patients are advised to have intercourse after three days of complete menstrual cleansing.