Men continue to have a strong interest and commitment to effective family planning. A male contraceptive must reduce the number of fertile sperm reaching the site of fertilization either by reducing or diverting sperm delivery or inhibiting fertilizing capacity. Traditional, widely used male-dependent methods include periodic abstinence, non-vaginal ejaculation, condoms, and vasectomy. But the reversible methods are not reliable, and the reliable method is not intended reversible. Over seven decades, numerous reversible, reliable and affordable hormonal contraceptives were marketed for women, but no new male contraceptive has been introduced for centuries. For men to share more equally the burdens and benefits of family planning, more effective, reversible male contraceptive methods are needed.
Progress in hormonal male contraception
Public sector research (WHO’s Human Reproduction Program, Population Council, NICHD) has investigated hormonal methods, analogous to female hormonal contraception, which are closest to creating a reliable, reversible male contraceptive method. Landmarks were the two WHO male contraceptive efficacy studies, the first to count pregnancies, not just sperm. Subsequent public sector research refined the target for adequate sperm suppression (<1 million/ml) and optimized hormonal regimens (combination androgen + progestin). Multiple combination hormonal regimens have shown high contraceptive efficacy with reliable, reversible suppression of sperm output and few side effects. Although clinical research into efficacy and safety of novel male contraceptive methods is completed in the public sector, private sector product development, indispensable for marketing, ceased decades ago ignoring the low-hanging fruit. Paradoxically, clinical hormonal male contraceptive research is far more advanced than was female hormonal contraception when first proven in 1960.
Progress in non-hormonal male contraception
The failure to develop hormonal methods for men has redirected efforts to inventing a non-hormonal contraceptive method for men on the spurious grounds of better safety and/or efficacy. Yet no non-hormonal contraceptives directed as oocytes was ever developed for women while novel tubal occlusion methods have encountered off-target toxicity. Numerous approaches directed at reversible inhibition of sperm metabolism &/or fertilizing capacity are reported in convincing pre-clinical models, off-target human toxicity and the ethical/practical challenges of testing human sperm fertilizing capacity remain formidable.
Commercial development factors – market failure and reasons
The current stasis is because the public, medical and health demand for a male contraceptive is not matched by the private sector product development, constituting a classical market failure. Reasons for the mismatch include risks from low profitability (vs low-cost female contraceptives), high bar for safety in treating healthy men with high risk of predatory product liability suits for new contraceptives in pursuit of deep pockets. Market failures for commercially non-viable products are partially remedied for drug treatments of rare conditions (orphan drugs, snake anti-venoms) or public health emergency (COVID vaccine). Ultimately, fatal market failure can only be overcome by a public sector initiative valuing the need to develop a safe, reliable and reversible male contraceptive product.