Intrauterine devices are contraceptives inserted by doctors or expert nurses in the uterus through the vagina. Copper releasing IUDs such as the Copper T act by increasing phagocytosis of sperms within the uterus and the Copper ions released suppress sperm motility and the fertilizing capacity of sperms. Ovulation is controlled by FSH and LH hormones. Copper T doesn't prevent ovulation.