The IUD, also known as the intrauterine device, is a foreign body stimulator in the uterine cavity and has obvious hazards. 1. stimulation of the surrounding endometrial tissues can cause changes in the volume and duration of menstruation, most of which gradually improve in about three months. 2. abdominal pain, increased discharge or brown discharge after IUD placement, mainly caused by stimulation of mucosal tissues. 3. dislodgement or ectopic pregnancy after IUD placement. 4. The IUD can be placed in the pelvic cavity by improperly handling the ring, which requires surgery to remove it. 5. The IUD with the tail wire continuously stimulates the cervix and vagina, causing vaginitis and cervicitis, and may also cause penile damage during sex. The specific hazards that arise are related to the nature, size and shape of the ring, which is regularly checked at the hospital after placement and replaced in time if necessary.