There are many reasons for significant vaginal bleeding after sex, mainly including bleeding caused by rupture of the hymen of the first sexual intercourse, endometrial shedding caused by sexual intercourse, or contact bleeding. In the case of women who are having sex for the first time, it will have an obvious dilating effect on the vaginal wall and at the same time may cause the hymen to rupture, thus leading to bleeding, which is a normal physiological phenomenon and does not require conditioning treatment. Temporarily stop having sex and it will soon return to normal. If it is not the first time for women to bleed during sex, it is possible that the vagina may be damaged due to excessive force during sex before and after menstruation, but if it does not occur frequently, no special treatment is needed. If the bleeding is obvious every time you have sex, it is contact bleeding, which may be cervical erosion, cervical polyps or cervical cancer, and you need to go to the hospital for further examination.