Intrauterine devices (IUDs) are inserted by a doctor into a woman’s uterus through the vagina. IUDs are T-shaped and made of molded plastic. Some types of IUDs release a progestin called levonorgestrel. Another type has a copper wire wrapped around the base and on the arms of the T. Plastic strings are attached to the IUD. The string enables a woman to make sure the device is still in place and a doctor to easily remove it.