Ovarian function with a novel combined contraceptive vaginal ring.

Background: NuvaRing is a combined contraceptive vaginal ring designed for 3 weeks continuous use followed by a 1 week ring-free period. The present study evaluated ovarian function in women who were instructed to either adhere to, or deviate from, the recommended regimen of use.

Methods: In this open-label, randomized study, 45 women aged between 18 and 35 years used NuvaRing for one cycle in which the ring was used according to the recommended regimen. Women in group A (n = 15) then continued with a 'normal' 3 week period of ring use after which the restoration of ovarian function-i.e. the time to ovulation-for each woman was determined by daily vaginal ultrasound and serum hormone levels. For women in group B (n = 15), the second cycle consisted of only 3 consecutive days of ring use, after which each woman was monitored until ovulation. Women in group C (n = 15) were not permitted to start a second 'normal' cycle until a follicle with a diameter of 13 mm was observed by vaginal ultrasound; subsequently, the development of these follicles during the second cycle of ring use was monitored daily.

Results: Irrespective of the length of the second cycle, 3 weeks (group A) versus 3 days (group B), a new cohort of follicles needed to be recruited and the time to ovulation after ring removal was similar (19 versus 17 days). The median time needed to develop a follicle up to 13 mm in diameter (group C) was 11 days (range 8-21 days); none of the women ovulated after insertion of the second ring.

Conclusion: NuvaRing is a highly effective, reversible method of hormonal contraception. Ovulation, at least until the stage of a 13 mm dominant follicle, is prevented and as little as 3 consecutive days of NuvaRing use interferes with follicle growth.