If you have been wearing the IUD for a long time, you may bleed during intercourse, and the cause of bleeding is mostly related to the displacement of the IUD. When the IUD has been in place for too long, the position of the IUD may change due to aging of the IUD, excessive menstruation, infection and other factors. When having sex, the uterus will contract under external stimulation, and the displaced IUD may cause the uterus or cervical mucosa to break, resulting in bleeding. If the position of the IUD is normal, but there are symptoms of contact bleeding, it may be due to cervical polyps, cervicitis, vaginitis and other inflammatory diseases resulting in mucosal congestion and edema, which will lead to mucosal rupture due to stimulation during sexual intercourse, resulting in bleeding symptoms. Therefore, if you have bleeding symptoms during sex, you should go to the hospital for ultrasound and other relevant examinations to clarify the position of the IUD, confirm the cause of the bleeding, and treat the cause in a timely manner.