Objective: To assess the effects of the combined contraceptive vaginal ring NuvaRing on ovarian function.

Design: Randomized, open-label, crossover study.

Setting: Clinical pharmacology unit.

Participant(s): Sixteen healthy female volunteers.

Intervention(s): Group 1: one cycle of combined oral contraceptive containing desogestrel (150 microg) and ethinyl estradiol (30 microg) (desogestrel/EE COC), followed by a NuvaRing treatment period. Group 2: NuvaRing treatment period followed by a cycle of desogestrel/EE COC.

Main outcome measure(s): Follicular diameter, serum hormone concentrations (follicle-stimulating hormone, 17beta estradiol, luteinizing hormone, and progesterone), and endometrial thickness.

Result(s): NuvaRing use for the recommended period of 3 weeks resulted in complete inhibition of ovulation, as assessed by vaginal ultrasound (follicular diameter) and by serum luteinizing hormone and progesterone concentrations. Inhibition of ovulation was maintained for an additional 2 weeks of NuvaRing use. Ovarian suppression between the groups was comparable. Furthermore, ovarian suppression after 3 weeks of NuvaRing use was comparable to that on day 21 of DGS/EE COC intake. NuvaRing was well tolerated.

Conclusion(s): NuvaRing completely inhibited ovulation throughout the normal 3-week period and the extended period of use. Ovarian suppression was comparable to that with desogestrel/EE COC.