Fertility and combined oral contraceptives – unintended pregnancies and planned pregnancies following oral contraceptive use – results from the INAS-SCORE study

Abstract

Abstract Objectives: To estimate the real-use contraceptive effectiveness of the combined oral contraceptive containing dienogest and estradiol valerate (DNG/EV) and whether DNG/EV compared to other combined oral contraceptives (oCOC) has a negative effect on return to fertility. Methods: Transatlantic, prospective, non-interventional cohort study conducted in the USA and seven European countries with two main exposure groups and one exposure subgroup: new users of DNG/EV and other COC (oCOC), particularly levonorgestrel-containing COCs (LNG). In a planned secondary analysis, pregnancy outcomes were investigated including contraceptive effectiveness and pregnancy following contraceptive cessation. The influence of age, parity and OC-type were assessed. Results: 50,203 COC users were followed for 105,761 woman-years (WY). There were 677 unintended pregnancies reported: 451 in the USA and 226 in Europe. The contraceptive failure rate in Europe was 0.5 events/100 WY (95% CI: 0.4–0.5) and in the USA 1.9 events/100 WY (95% CI: 1.7–2.1). Differences in compliance (1.3 pregnancies/100 WY) accounted for 90% of the geographical difference seen between Europe and the USA. DNG/EV showed lower contraceptive failure rates compared to the comparators; 0.9% DNG/EV, 2.1% oCOC and 2.8% LNG after 4 years. Overall, 1167 (2.3%) of women stopped contraceptive use with the intention of becoming pregnant with 89% conceiving within 2 years. No significant differences were seen between groups after adjusting for age. Conclusion/Discussion: DNG/EV is associated with similar contraceptive effectiveness in typical-use settings when compared to oCOC and LNG. There was no difference observed between cohorts in fertility following OC use.