NOMAC-E2 shows a better contraceptive effectiveness than LNG combined oral contraceptives in women under 25: real-world PRO-E2 study

Abstract

Objective: To investigate unintended pregnancy and changes in mood, acne, and weight in NOMAC-E2 vs levonorgestrel-containing COC (COC_LNG) users under 25 years.Methods: In this large, observational study, new users (first-ever users of an eligible COC or restarting with the same or a new eligible COC after a break of at least 2 months) of NOMAC-E2 and COC_LNG were recruited in 12 countries in Europe, Australia, and Latin America and followed up via questionnaires for up to 2 years. Unintended pregnancy was expressed by the Pearl Index (PI; contraceptive failures/100 women-years). Crude (HR_crude) and adjusted hazard ratios (HR_adj) were calculated. Mood and acne changes were defined as change of score from baseline. Weight change was defined as percent change of body weight.Results: Overall, 12,829 NOMAC-E2 users and 17,095 COC_LNG users under 25 were followed-up. The risk of unintended pregnancy was statistically significantly lower in the NOMAC-E2 cohort; confirmed events: 30 NOMAC-E2 (PI 0.24; 95% CI, 0.16-0.35) vs 94 COC_LNG (PI 0.51; 95% CI, 0.41-0.62). The HR_crude for unintended pregnancy comparing NOMAC-E2 to COC_LNG was 0.47 (95% CI, 0.31-0.71) and the HR_adj was 0.52 (95% CI, 0.34-0.78). No differential effect on acne, mood, and weight was observed between cohorts.Conclusions: NOMAC-E2 shows a significantly better contraceptive effectiveness in young women and has no differential effect on acne, mood, and weight compared to COC_LNG.

Keywords: NOMAC-E2; contraceptive effectiveness; contraceptive failure; estradiol; levonorgestrel; nomegestrol acetate; unintended pregnancy.