An Intrauterine Device (or IUD) is a small, T-shaped contraceptive device that is inserted into the uterus. It is designed to prevent pregnancy by interfering with sperm movement and creating a hostile environment for fertilization. IUDs are considered one of the most effective forms of reversible contraception. There are 2 variations of IUDs- hormonal and non-hormonal. Hormone IUDs are also used to decrease heavy bleeding.