Bleeding during the third sexual intercourse may be caused by bleeding from the hymenal stump, broken vaginal mucosa or cervical diseases. 1. Bleeding from the hymen stump: If the hymen is ruptured and the shape of the hymen is different, there may still be bleeding during the first few times of sexual intercourse. 2. Vaginal mucous membrane breakage: If there is rough behavior during sex, it may damage the vaginal mucous membrane or the skin of the vaginal opening and cause bleeding. 3. Cervical diseases: If there is cervicitis or cervical erosion, it is more likely to lead to bleeding during sex, which may be accompanied by lumbar pain, abdominal distension, lower abdominal pain or abnormal secretions. Bleeding during sex may also have other causes, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of a professional doctor.