The effects of a new low-dose combined oral contraceptive containing levonorgestrel on ovarian activity.

The effects of a new low-dose oral contraceptive (OC) on ovarian activity were assessed in an open-label study involving 15 healthy women in Germany. After an ovulatory pretreatment cycle subjects were treated for 3 consecutive cycles with an OC containing 100 mcg of levonorgestrel and 20 mcg of ethinyl estradiol. The effects on ovarian activity were characterized by vaginal ultrasonography and hormonal assays. 2 women dropped out of the study: 1 due to intracyclical bleeding and 1 because of depressed mood and diarrhea. All treatment cycles were anovulatory. 3 of the 13 women who completed the study did not exhibit any follicular development growth in the endometrium or significant elevation in hormone levels. The remaining 10 women had significant suppression of cyclic ovarian follicular activity. 6 of these women exhibited some ovarian activity characterized by follicular development and different profiles in hormonal parameters without elevated progesterone levels. In 5 of these cases follicles developed and persisted as follicle-like structures through the pill-free interval and into the next cycle at which time they disappeared or extensively reduced their size. In 4 other cases follicle-like structures developed along with significant changes in the hormone profiles. The greatest degree of ovarian activity and steroidal hormone production occurred at the end of the OC cycle just before the induced withdrawal bleed. The lack of ovarian-endometrial synchronization along with progestin-induced cervical mucus hostility are important adjuncts to the suppression of ovulation associated with low-dose OCs.