OBJECTIVES: To compare bleeding patterns for 12months 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 4days "treatment withdrawal" to stop bleeding.
STUDY DESIGN: Women, 66 to each group, were randomized to continuous use of a CVR (15mcg ethinyl estradiol/150mcg etonogestrel) or a low-dose pill (20mcg ethinyl estradiol/100mcg levonorgestrel) for 360days 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 4days stopped a bleeding episode within 5days 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 1year 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 12months using a menstrually signaled regimen will give women an indication of what to expect with continuous use.