GNRH1 and endometriosis: Thus, in all studies in premenopausal women with endometriosis in which long-term AIs have been used, they have been associated with gonadotropin-releasing hormone (GnRH) analogues, to slow down gonadotropins and produce hypoestronism, or with progestins or oral contraceptive pills (OCP), which could also improve endometriosis and its symptoms.