The mechanism of action is to inhibit the hypothalamic-pituitary-ovarian axis (H-P-O axis), thus inhibiting the cyclic synthesis and release of pituitary gonadotropins, which in turn inhibits the development and maturation of follicles in the ovary, and ultimately inhibits ovulation. It also serves to counteract androgens and inhibit endometrial hyperplasia. But in addition to the function of contraception, what other roles does the pill have? A. Improve dysmenorrhea: Dysmenorrhea refers to pain and swelling in the lower abdomen before and after menstruation or during menstruation, accompanied by lumbago or other discomfort, and the symptoms seriously affect the quality of life. Ninety percent of dysmenorrhea is primary, and research has proven that the important cause of primary dysmenorrhea is high levels of prostaglandins. High levels of prostaglandins in women during ovulation cause ischemia of the uterine muscles and contraction of the uterus resulting in dysmenorrhea. COC can reduce the endometrial thickness and inhibit ovulation, which can also reduce the secretion of prostaglandins through negative feedback, thus relieving dysmenorrhea or making it disappear. Dysfunctional uterine bleeding (gong hemorrhage): Gong hemorrhage refers to abnormal bleeding from the uterus due to malfunction of the regulation mechanism of the neuroendocrine system, mainly manifested as frequent, scanty and excessive menstruation, excessive and irregular bleeding. The anovulatory type of functional uterine bleeding accounts for 70% to 80% of cases, mostly seen in adolescence and perimenopause. When organic lesions of the reproductive tract are excluded, contraceptives can be used to stop bleeding, in which estrogen stops bleeding by maintaining the growth of the endometrium, increasing the thickness of the endometrium and preventing breakthrough bleeding, and progesterone stops bleeding by protecting the endometrium so that the endometrial glands secrete and the interstitial metaplasia-like atrophy stopping bleeding. Therefore, COC is generally used to stop bleeding in adolescent dysfunctional uterine bleeding, while progesterone should be used to stop bleeding in perimenopausal dysfunctional uterine bleeding by making the endometrium atrophy. Endometriosis: The main symptoms of endometriosis are pain and infertility, the treatment principle is mainly surgery, supplemented by drugs, and suppression of ovarian function is the best drug treatment. During use, there is 1 withdrawal bleeding per month, which relieves pain and stops the progression of the disease, as well as contraception. Therefore, it is suitable for those who have children or do not want to have children, but can resume ovulation and fertility after stopping the drug. American obstetrics and gynecology scholars recommend: endometriosis after surgery can be long-term cyclical use of oral contraceptives, but it is best to make a routine physical examination once a year . COC can inhibit ovulation, lower estrogen levels, maintain estradiol at early follicular levels, cause ectopic endometrial lesions in the myometrium to atrophy to varying degrees, and decrease function, thus relieving the symptoms of dysmenorrhea and preventing the development of lesions. If fertility is not required, it can be used for a long time, but patients should be observed and followed up: including lesions, blood lipids, blood coagulation, liver and kidney function and whether there is recurrence after stopping the drug. V. Polycystic ovary syndrome (POCS): POCS is a group of clinical syndromes of unknown etiology and highly heterogeneous clinical manifestations, characterized by anovulation and hyperandrogenemia. COC can reduce androgen production and circulating androgen levels and activity by: (1) inhibiting the hypothalamic-pituitary-ovarian axis, reducing ovarian size; preventing excessive endometrial hyperplasia and controlling the menstrual cycle; (2) increasing plasma sex hormone-binding globulin (SHBG) and decreasing free testosterone and dehydroepiandrosterone (DHT), thereby reducing androgen production and circulating androgen levels and activity, and counteracting peripheral hyperandrogenism. (3) Protecting the endometrium and counteracting the effect of single estrogen on the endometrium; thus achieving relief of polycystic ovary syndrome.