Caption

IUD. A woman holds a progestogen- loaded intrauterine contraceptive device (IUD). An IUD is inserted through the cervix into the uterus, where it may remain for a number of years. The plastic string (top) hangs through the cervix, allowing easy removal. Just how the device works is not understood, but it is thought to prevent implantation of fertilized eggs in the wall of the uterus. This IUD contains a progestogen drug, which suppresses ovulation, makes cervical mucus impenetrable to sperm, and inhibits implantation of fertilized eggs in the uterus.