Gonadotropin-releasing hormone antagonist / estrogen / progestin combinations are used to treat endometriosis and heavy menstrual bleeding caused by uterine fibroids. These medications work by lowering estrogen and progesterone levels in your body, while adding a small amount of these hormones back to lessen the chance of serious side effects. An example is relugolix / estradiol / norethindrone (Myfembree).