Hormonal contraception for men: Limitations

Eberhard Nieschlag

Institute of Reproductive Medicine of the University of Münster, (WHO Collaboration Centre for Research in Male Reproduction), Münster, Germany

As opinion polls show, men are ready for hormonal male contraception and would use an effective preparation if it became generally available. However, they would prefer a pill over any other mode of application. Notwithstanding, modalities for male contraception currently under investigation favour testosterone and gestagen injections or implants of a combination of both as they provide the constant serum levels required for suppression of gonadotropins and spermatogenesis. This implies that the contraceptive will not be self administered, but will rather require medical assistance for initiation and possibly also for termination. The contraceptive protection provided by a hormonal male method will have a relatively slow onset as, on average, three months are required to achieve the necessary azoospermia or at least severe oligozoospermia. Therefore, use of hormonal male contraception will require careful planning and will be used preferentially by couples in stable relationships. Similarly, recovery of spermatogenesis after cessation of hormonal male contraception is relatively slow requiring 3-6 months to regain full fertility. Since most clinical trials so far did not exceed one year, it is unclear whether longer use may result in prolonged recovery phases. Non- uniformity of suppression of spermatogenesis under a given regimen remains an important limitation. There are ethnic differences (East Asian men respond better than Caucasians), but also differences within a population which could not yet be explained by a mechanism that would allow a rational approach to counteract it. Until this goal is reached it may be necessary to investigate whether a volunteer has achieved azoospermia or not, i.e. semen analysis would be required before contraceptive protection can be guaranteed. These investigations would complicate the use of a male hormonal contraceptive, but would be similar to the requirements after vasectomy.