Ovarian activity in women taking an oral contraceptive containing 20 μg ethinyl estradiol and 150 μg desogestrel:: Effects of low estrogen doses during the hormone-free interval

OBJECTIVE: We assessed the effect of low ethinyl estradiol doses given during the nominally hormone-free interval of the Mircetter(TM) (brand of desogestrel/ethinyl estradiol and ethinyl estradiol) contraceptive regimen on ovarian activity. STUDY DESIGN: In a randomized, double-blind study, healthy women received 150 mu g desogestrel and 20 mu g ethinyl estradiol for 21 days followed by either placebo for 7 days (Mircette(TM)/placebo; N = 24) or placebo for 2 days and 10 mu g ethinyl estradiol for 5 days (Mircette(TM)/ethinyl estradiol; N = 23). RESULTS: During cycles 2 and 3, the Mircette(TM)/placebo group had a higher incidence of persistent ovarian follicles (eight subjects versus three subjects) and on average a greater maximum follicle diameter than the Mircette(TM)/ethinyl estradiol group. One Mircette(TM)/placebo subject probably ovulated in cycle 2, and another had a luteinized unruptured follicle; no such activity was seen in the in the Mircette(TM)/ethinyl estradiol group. The study medication was well tolerated, and there were no apparent between-group differences in vaginal bleeding patterns. CONCLUSION: The Mircette(TM) regimen, which includes low ethinyl estradiol doses during the hormone-free interval, more effectively suppresses ovarian follicular activity with a low monthly estrogen dose.