Pooled analysis of two phase 3 trials evaluating the effects of a novel combined oral contraceptive containing estetrol/drospirenone on bleeding patterns in healthy women

Objective: To evaluate the bleeding patterns of a new combined oral contraceptive containing estetrol (E4) 15 mg/drospirenone (DRSP) 3 mg in a 24/4-day regimen. Study design: We pooled bleeding data from two parallel, open-label, 13-cycle phase 3 trials that enrolled participants 16 to 50 years old with body mass index (BMI) ≤35 kg/m². Participants reported vaginal bleeding/spotting in daily diaries. For this bleeding analysis, we included participants with at least one evaluable cycle. We calculated mean frequencies of scheduled and unscheduled bleeding/spotting episodes and median duration of bleeding/spotting episodes, and assessed associations between treatment compliance, BMI and recent hormonal contraceptive use on bleeding/spotting outcomes. Results: We included 3409 participants with 33,815 cycles. Scheduled bleeding/spotting occurred in 87.2% to 90.4% of participants/cycle, with a median duration of 4 to 5 days. Unscheduled bleeding/spotting decreased from 27.1% in Cycle 1 to 20.6% in Cycle 2 to ≤17.5% from Cycle 5 onwards. Most (66.5%) unscheduled bleeding/spotting episodes were spotting-only. Between 5.8% and 7.8% of users/cycle experienced absence of any scheduled or unscheduled bleeding/spotting. Missing one or more active pills resulted in a higher occurrence of unscheduled bleeding/spotting (adjusted odds ratio [aOR] 2.13 [95% confidence interval 1.68–2.70]) and absence of scheduled bleeding/spotting (aOR 2.36 [1.82−3.07]). Participants with a BMI ≥30 kg/m² reported more absence of scheduled bleeding/spotting (aOR 1.68 [1.37−2.05]). Switchers and starters reported similar frequencies of unscheduled bleeding/spotting (aOR 0.94 [0.83−1.07]) and absence of scheduled bleeding/spotting (aOR 1.00 [0.85−1.19]). Three percent of participants discontinued for a bleeding-related adverse event. Conclusion: E4/DRSP use results in a predictable bleeding pattern with limited unscheduled bleeding/spotting. Noncompliance and BMI affect bleeding patterns. Implications statement: Most estetrol/drospirenone users experience a predictable and regular bleeding pattern. Providers can educate patients about the expected bleeding patterns and should advise users that they may infrequently experience no scheduled bleeding/spotting. This information may improve user acceptability and continuation of this new oral contraceptive.