Pulsatile luteinizing hormone patterns in long term oral contraceptive users

Oral contraceptives (OC) inhibit folliculogenesis by a central suppressive action on the release of gonadotropins. To characterize the nature of these central effects, we studied 40 long term OC users on 3 different OCs: two monophasic preparations with 30 micrograms ethinyl estradiol and 150 micrograms l-norgestrel (group 1; n = 15), 150 micrograms desogestrel (group 2; n = 10), and a triphasic formulation containing 30-40 micrograms ethinyl estradiol and 50, 75, and 125 micrograms l-norgestrel (group 3; n = 15). Blood sampling at 10-min intervals during 6-h periods was performed at different moments in the pill cycle. Thirteen healthy volunteers with regular ovulatory cycles served as normal controls. FSH and LH were measured by a sensitive immunoradiometric assay. Pulsatile LH release was observed in all OC users. Mean serum LH and FSH levels, number of LH pulses per 6 h, and the amplitude of LH pulses on day 1 of the pill cycle did not differ from early follicular phase control values. FSH levels were...