Hopes for new male contraception: Are they realistic?
Eberhard Nieschlag (Germany)
Centre of Reproductive Medicine and Andrology, University Hospitals, 48149 Münster, Germany
The world population continues to grow rapidly while resources for sustainable living dwindle and manmade ecological problems increase proportionally to the overpopulation. Family planning is required to reduce population growth in developing countries and to stabilize populations in developed countries. Contraception makes abortion superfluous and provides the key to family planning. Women increasingly demand that men share the burden and risks of contraception and – as opinion polls show – men would be willing to use contraceptives if they were available. Research has established the principle of hormonal male contraception based on suppression of gonadotropins and spermatogenesis. All hormonal male contraceptives use testosterone, but only in East Asian men can testosterone alone suppress spermatogenesis to a level compatible with contraceptive protection. In Caucasians additional agents are required of which progestins are favoured. Clinical trials concentrate on testosterone combined with norethisterone, desogestrel, etonogestrel or DMPA. The first randomized, placebo-controlled clinical trial performed by the pharmaceutical industry demonstrated the effectiveness of a combination of testosterone undecanoate and etonogestrel in suppressing spermatogenesis in volunteers. However, the two companies involved left the field of male contraception when they were taken over by other firms. Hopes now rest on organisations such as WHO and the Population Council that they may develop modalities for male contraception attractive enough to be marketed by industry.