Randomized comparison of bleeding patterns in women using a combined contraceptive vaginal ring or a low-dose combined oral contraceptive on a menstrually signaled regimen.

OBJECTIVES: To compare bleeding patterns for 12 months continuous use of a contraceptive ring [contraceptive vaginal ring (CVR)] and pill [combined oral contraceptive (COC)] on a menstrually signaled regimen and the effectiveness of 4 days "treatment withdrawal" to stop bleeding.

STUDY DESIGN: Women, 66 to each group, were randomized to continuous use of a CVR (15 mcg ethinyl estradiol/150 mcg etonogestrel) or a low-dose pill (20 mcg ethinyl estradiol/100 mcg levonorgestrel) for 360 days on a menstrually signaled regimen. Bleeding/spotting days, daily use of ring or pill, was recorded. Endpoint was the total number of bleeding/spotting days for each method over four 90-day reference periods (RP) plus the analysis of bleeding patterns using modified World Health Organization criteria.

RESULTS: There was a reduction in the mean (±S.D.) number of bleeding/spotting days from RP1 (CVR 14.2±10; pill 16.6±10.9) to RP4 (CVR 8.8±9.6; pill 8.8±9.1). Fifteen percent of CVR and 4% COC users experienced amenorrhea or infrequent bleeding throughout the study. Amenorrhea increased over time (RP1 vs. RP4: CVR 10% vs. 21% and COC 2% vs. 30%). Compliance with the menstrually signaled regimen was poor. Ceasing hormones for 4 days stopped a bleeding episode within 5 days in the majority of episodes and many stopped spontaneously.

CONCLUSION: Bleeding patterns with continuous use of the CVR and COC are similar and improve over 1 year of use. The unpredictability, but short duration, of bleeding episodes should be stressed during counseling.

IMPLICATION: This information for clinicians and women about breakthrough bleeding patterns with use of a CVR or combined pill over 12 months using a menstrually signaled regimen will give women an indication of what to expect with continuous use.