Ovarian function with the contraceptive vaginal ring or an oral contraceptive: a randomized study.

Background: The effects on ovarian function of the combined contraceptive vaginal ring NuvaRing and a combined oral contraceptive (COC) were compared.

Methods: This randomized, open-label study was performed in 40 healthy female volunteers, who were randomized by a computer-generated list after stratification for the ovulation day in a pretreatment cycle. They received two cycles of NuvaRing (21 subjects) or a COC (30 microg ethinylestradiol and 150 microg levonorgestrel, 19 subjects). NuvaRing was started on cycle day 5, COC on cycle day 1. Follicular diameter, endometrial thickness and FSH, LH, 17beta-estradiol (E2) and progesterone concentrations were determined.

Results: The median maximum follicular diameter (maxFD) was < or =11 mm during treatment. In the first treatment cycle the maxFD was lower in the COC than in the NuvaRing group, due to the different starting procedures. MaxFD were not different in the second treatment cycle. In both groups, E2 and progesterone levels remained low during treatment. Ovulations did not occur.

Conclusions: In both groups, ovarian activity was adequately suppressed. Due to the different starting procedures, lower ovarian activity was observed in the COC group in the first treatment cycle. In the second cycle, ovarian suppression was comparable with NuvaRing and COC treatment.