Oral contraceptive acts by

Neither estrogen nor progestin hormone dose used in combination hormonal oral contraceptives alone would be able to suppress ovulation but together the estrogen and progestin hormones work synergistically to suppress ovulation "successfully". The synergistic antiovulatory effect from the combined use of estrogen and progestin directly decreases the secretion of the gonadotropin-releasing hormone from the hypothalamus and is considered the main action. This negative feedback mechanism disrupts ovulation by interfering with the hypothalamus-pituitary-ovary axis and gonadotropin secretion from the pituitary. Specifically, the progestin component suppresses luteinizing hormone release and the LH surge, which is necessary for ovulation, and the estrogen component suppresses the follicle stimulating hormone, which prevents the selection and maturation of the dominant follicle.