Caption

IUD. Close-up of a type of Intrauterine Contraceptive Device (IUD). This IUD consist of a piece of moulded plastic that is inserted into the uterus. A coil of copper wire is wrapped around the stem. A piece of plastic string (at bottom) hangs through the cervix, allowing easy removal. Exactly how IUDs work is not understood, but they are thought to prevent implantation of fertilized eggs in the wall of the uterus. The probability of a pregnancy for each year of use is 2-3%. IUDs with copper coils need to be replaced every 3-5 years.