Non-contraceptive use
The hormones in the pill have also been used to treat other medical conditions, such as polycystic ovary syndrome (PCOS), endometriosis, adenomyosis, acne, hirsutism, amenorrhea, menstrual cramps, menstrual migraines, menorrhagia (excessive menstrual bleeding), menstruation-related or fibroid-related anemia and dysmenorrhea (painful menstruation). Besides acne, no oral contraceptives have been approved by the U.S. FDA for the previously mentioned uses despite extensive use for these conditions. PCOS
The cause of PCOS, or polycystic ovary syndrome, is multifactorial and not well-understood. Women with PCOS often have higher than normal levels of luteinizing hormone (LH) and androgens that impact the normal function of the ovaries. While multiple small follicles develop in the ovary, none are able to grow in size enough to become the dominant follicle and trigger ovulation. This leads to an imbalance of LH, follicle stimulating hormone, estrogen, and progesterone. Without ovulation, unopposed estrogen can lead to endometrial hyperplasia, or overgrowth of tissue in the uterus. This endometrial overgrowth is more likely to become cancerous than normal endometrial tissue. Thus, although the data varies, it is generally agreed upon by most gynecological societies that due to the unopposed estrogen, women with PCOS are at higher risk for endometrial cancer.To reduce the risk of endometrial cancer, it is often recommended that women with PCOS who do not desire pregnancy take hormonal contraceptives to prevent the effects of unopposed estrogen. Both COCPs and progestin-only methods are recommended. It is the progestin component of COCPs that protects the endometrium from hyperplasia, and thus reduces a woman with PCOSs endometrial cancer risk.
Combined hormonal contraceptives, including COCPs, inhibit follicular development and prevent ovulation as a primary mechanism of action.Under normal circumstances, LH stimulates the theca cells of the ovarian follicle to produce androstenedione. The granulosa cells of the ovarian follicle then convert this androstenedione to estradiol. This conversion process is catalyzed by aromatase, an enzyme produced as a result of FSH stimulation. In individuals using oral contraceptives, progestogen negative feedback decreases the pulse frequency of gonadotropin-releasing hormone (GnRH) release by the hypothalamus, which decreases the secretion of follicle-stimulating hormone (FSH) and greatly decreases the secretion of luteinizing hormone (LH) by the anterior pituitary. Decreased levels of FSH inhibit follicular development, preventing an increase in estradiol levels. Progestogen negative feedback and the lack of estrogen positive feedback on LH secretion prevent a mid-cycle LH surge. Inhibition of follicular development and the absence of an LH surge prevent ovulation.Estrogen was originally included in oral contraceptives for better cycle control (to stabilize the endometrium and thereby reduce the incidence of breakthrough bleeding), but was also found to inhibit follicular development and help prevent ovulation.