The PRO-E2 study was a large, prospective, observational, active surveillance study conducted in 12 countries across Europe and Latin America, and in Australia. PRO-E2compared users of NOMAC-E2 with users of mainly combined oral contraceptives with levonorgestrel (COC-LNG). In total, 101,498 women were recruited by healthcare professionals under real-life clinical conditions between August 2014 and September 2019.