Sex during menstruation may lead to prolonged periods, increased menstrual flow, endometriosis, gynecological inflammation, etc., which are generally unrelated to the presence or absence of contraception. During menstruation, because of the endometrial shedding of bleeding, as well as pelvic congestion, sexual intercourse at this time may stimulate the capillary rupture increase, resulting in prolonged menstruation or increased menstrual flow. At the same time, it is easy for the shed endometrium to plant in other parts of the body, causing endometriosis. During menstruation, the resistance will be reduced, and it is easier to bring bacteria into the vagina after sex, which will easily lead to bacterial infection and cause gynecological inflammation, resulting in endometritis, cervicitis, vaginitis, pelvic inflammatory disease and so on. Therefore, sexual intercourse should be avoided during menstruation to avoid adverse effects on the body.