Menstruation is not yet clean, coitus may lead to the following results: 1, will cause inflammation of the reproductive tract, because menstruation for the endometrium shedding caused by vaginal bleeding, menstruation is not yet completely clean when the endometrium is not yet fully repaired, so coitus may lead to pathogenic bacterial infections, resulting in cervicitis or endometrial inflammation, and in severe cases, may also result in pelvic inflammatory disease; 2, menstruation is not yet completely clean, the uterus cavity there are still The blood is still in the uterine cavity, coitus will stimulate the uterine contraction, uterine contraction will make the blood enter the pelvis along the fallopian tube, clinically can lead to endometriosis. Therefore, it is not possible to have intercourse during menstruation, and it is best to have intercourse three days after the menstruation is completely clean.