Efficacy and Safety of an Injectable Combination Hormonal Contraceptive for Men

Context: The development of a safe and effective reversible method of male contraception is still an unmet need. Objective: Evaluation of suppression of spermatogenesis and contraceptive protection by coadministered im injections of progestogen and testosterone. Design: Prospective multicentre study. Setting: Ten study centers. Participants: Healthy men, aged 18–45 years, and their 18- to 38-year-old female partners, both without known fertility problems. Intervention: Intramuscular injections of 200-mg norethisterone enanthate combined with 1000-mg testosterone undecanoate, administered every 8 weeks. Main Outcomes Measures: Suppression of spermatogenesis by ejaculate analysis, contraceptive protection by pregnancy rate. Results: Of the 320 participants, 95.9 of 100 continuing users (95% confidence interval [CI], 92.8–97.9) suppressed to a sperm concentration less than or equal to 1 million/mL within 24 weeks (Kaplan-Meier method). During the efficacy phase of up to 56 weeks, 4 pregnancies occurred among...