If bleeding occurs under intercourse, it may be clinically caused by the following reasons: First, the most common cause is early cervical cancer, which will cause contact bleeding, and clinical screening for cervical cancer is recommended. Secondly, intercourse after pregnancy will stimulate to cause the detachment between the gestational sac and the uterine wall, which will also result in vaginal bleeding and cause the symptoms of preterm abortion. Thirdly, if you have intercourse with vaginal inflammation, such as trichomoniasis, clinically there will be bloody discharge, and when the bloody discharge comes out during intercourse, there will also be bleeding. Fourthly, if the action of intercourse is relatively rough, causing damage to the vulvar mucosa or vaginal mucosa, clinically bleeding may also occur. Therefore, once bleeding occurs during intercourse, a detailed examination should be done and treatment should be given according to the cause.