A contraceptive device that is inserted in the uterus. It works by preventing fertilization and/or implantation of a fertilized egg. IUDs are 99-percent effective with perfect use at preventing pregnancy. Prescribed and inserted by a health care provider, they cost several hundred dollars. This is not a method that was recommended or used by many teens and young women in the past because it typically prescribed after the birth of one or more children for women who want long-term protection against pregnancy but do not want to be surgically sterilized and who are not at risk for sexually transmitted diseases (STDs). However, they are now being recommended for young women even if they have never had a child.