Background: A cross-study analysis of contraceptive clinical trials for two different 91-day oral contraceptive (OC) regimens was performed to examine the impact on bleeding patterns when supplementing the 7-day hormone-free interval with 10 mcg ethinyl estradiol (EE) daily.
Study design: Two separate 1-year Phase 3 clinical programs were conducted using similar study designs. The percentages of subjects reporting bleeding and spotting using electronic diaries for each 91-day cycle were compared.
Results: Scheduled bleeding with the EE regimen was less than that reported with the regimen utilizing placebo during Days 85-91, with significant differences noted for all four 91-day cycles. Unscheduled bleeding decreased more quickly with the 91-day regimen containing low-dose EE in place of placebo, with significant differences noted during the third cycle.
Conclusions: This cross-study comparison suggests that the administration of low-dose estrogen in place of placebo in a 91-day extended regimen OC improves the bleeding profile.