Bleeding during intercourse after IUD is not normal menstruation but abnormal uterine bleeding, which is considered to be related to cervical lesions and displacement of the birth control device. 1. Cervical lesions: If a woman has cervical intraepithelial neoplasia or cervical erosion, she will have contact bleeding, i.e. a small amount of vaginal bleeding after sex. 2. Displacement of the birth control device: the uterus may contract after intercourse, which may lead to the displacement or dislocation of the birth control device, if the birth control device is stuck in the cervical opening to stimulate the local blood vessels, it will cause vaginal bleeding. For women who bleed during intercourse after IUD insertion, it is recommended that they go to the gynecology department of regular hospitals to improve ultrasound, cervical cancer screening and other related examinations, so as to clarify the cause of the disease and then actively treat it under the guidance of the doctor.