Aunt usually refers to menstruation, three days short of menstruation bleeding in the same room may be the result of menstruation, cervical disease, endometrial disease and so on. 1. menstruation: women’s menstruation by the environment, emotions, lifestyle and other factors, appear in advance or delayed up to a week is a normal phenomenon, this situation is likely to be the menstruation three days in advance. 2. Cervical diseases: If there are cervical diseases, it is easy to have coital bleeding, such as cervical ectropion, cervical polyps, cervical cysts, cervicitis, or cervical squamous intraepithelial lesion, cervical cancer and so on. 3. Endometrial diseases: some endometrial diseases can also cause irregular vaginal bleeding, which may occur after coitus, such as endometrial polyps, uterine fibroids, endometritis, endometrial cancer and so on. There are many reasons for bleeding during intercourse when you are three days short of menstruation, so it is recommended that you go to the hospital in time to find out the cause of the problem and then carry out targeted treatment.