Intrauterine devices (IUDs) are a form of long-term birth control. The IUD is typically a T-shaped implant that is placed by your doctor into your uterus. The implants use either hormones or copper to disable sperm and prevent fertilization of an ovum. IUDs that release progestin also thicken cervical mucosa, preventing sperm from entering the uterus. IUDs are considered a safe, effective and easily-reversible form of long-term birth control.