A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. III-Menstrual patterns. An international comparative trial.

Menstrual events among users of contraceptive vaginal rings (CVRs), releasing levonorgestrel and estradiol, were studied in comparison with a combined oral contraceptive, Nordette, in multicentered trials. CVRs were made with outside diameters of 50 and 58 mm and released about 250 micrograms and 290 microgram of levonorgestrel and 150 microgram and 180 microgram of estradiol per day, respectively. The CVRs were used continuously for 3 weeks and then removed for 1 week. Both the CVRs and Nordette were perceived to reduce menstrual flow and days of menstrual bleeding. Twenty to 25% of CVR users perceived increased intermenstrual bleeding or spotting. Diaries indicate, however, that on average, CVR users experienced about 1 day per month of bleeding or spotting with the ring in place. CVRs and Nordette produced approximately the same total number of bleeding and spotting days during 6 cycles of use, 27-29, but the small (50-mm OD) ring was associated with somewhat more spotting. This ring was also associated with somewhat more prolonged bleeding and spotting runs and with more prolonged nonbleeding intervals than reported by users of the larger (58-mm OD) ring or of Nordette. Differences among regimens, however, tended to be small even when statistically significant. Evidence from menstrual diaries indicates that these CVRs, and in particular 58-mm ring, provide control over the menstrual cycle comparable to the Nordette.