IUD. IUD An intrauterine device (IUD) is inserted into the uterus to prevent conception. The device can be withdrawn by pulling on the thread which extends to the vagina. Active” devices contain copper or progesterone, which changes the uterine mucosa and prevents implantation of the fertilized egg. Complications include infection of the uterine tube (salpingitis). Intrauterine devices are not recommended for women who have not had children. Here the IUD is shown in yellow with the threads u