progestin is a lab made version of a hormone that plays a role in the menstrual cycle and pregnancy. a variety of progestin treatments can stop menstrual periods and the growth the endometriosis tissue, which may relive symptoms. progestin therapies include a tiny device placed in the uterus that releases levonorgestrel (Mirena, Skyla, others), a contraceptive rod placed under the skin of the arm (Nexplanon), birth control shots (Depo-Provera) or a progestin-only birth control pill (Camila, Slynd)