The intrauterine device shown uses copper as the active contraceptive, others use progesterone in a plastic device. IUDs are very effective at preventing pregnancy (less than 2% chance per year for the progesterone IUD, less than 1% chance per year for the copper IUD). IUDs come with increased risk of ectopic pregnancy and perforation of the uterus and do not protect against sexually transmitted disease. IUDs are prescribed and placed by health care providers.Update Date: 9/19/2006 Updated by: Audra Robertson, MD, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.