The appearance of menstruation during intercourse may be a normal onset of menstruation, or it may be caused by endometrial disease or cervical disease. 1. Normal causes When a woman experiences menstruation during coitus, it may be that the coitus is during menstruation, and vaginal bleeding is normal menstrual bleeding, which is usually normal. 2.Pathological factors (1)Cervical diseases:Women who have vaginal bleeding during intercourse may not have normal menstruation, but contact vaginal bleeding, which may be caused by diseases such as cervicitis and cervical cancer. (2) Endometrial disease:Women who have menstruation during coitus may also have uterine bleeding caused by endometritis or endometrial cancer, which happens to flow out vaginally during coitus. In addition to normal causes, menstruation during intercourse may also be caused by cervical or endometrial diseases and other reasons. It is recommended that you go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment under the guidance of the doctor.