With the powerful tools of molecular investigation, the last decade has witnessed the most remarkable scientific advance in our history, yet no new leads for male contraception have been forthcoming. All the likely methods of male contraception discussed above were derived from relatively 'old' physiological principles or serendipitous observations. The increasing gap between fundamental research (in the control of mammalian spermatogenesis) and the lack of clinical application are a testament to the low public funding priority afforded to male reproduction and the unwillingness of the pharmaceutical industry to invest in male reproductive research and development. Yet amidst such an unfavourable setting and with very limited support, it is heartening to note that the prospects of introducing a new systemic method for male contraception into the market by the end of this millenium has been greatly enhanced. Thus the results of recent studies have confirmed the contraceptive efficacy of sex steroid-induced oligozoospermia and unexpectedly revealed an ethnically distinct pattern of susceptibility to the hormonal suppression of spermatogenesis. Thus, Asian men are more responsive than are caucasian, and long-acting testosterone esters now being tested in that most densely populated part of the world may well hasten the large-scale application of this method. This is probably the most effective way to correct the misconceptions that men are unwilling or disinterested in sharing in family planning options with their partners. Together with the increased acceptance of novel non-surgical and reversible methods of vas deferens occlusion and the availability of improved non-latex condoms, the currently unfulfilled contraceptive needs of millions of men can be increasingly met in future years. The consequent increase in overall contraceptive prevalence could well make the telling difference between demographic catastrophe and maintaining good quality existence. Politicians, scientists and industrialists need to wake up to their responsibilities and the opportunities offered by this untapped resource and market potential.
PIP: Vasectomy, withdrawal, and condoms account for at least 30% of total contraceptive usage in the world today. Needed, however, are modern contraceptive methods that can meet the needs and demands of men in the 21st century. The gap between fundamental research on mammalian spermatogenesis and its clinical application reflects the low priority afforded to male reproduction and an unwillingness on the part of the pharmaceutical industry to invest in such research. Reviewed, in this comprehensive article, are the current targets for male fertility control: suppression of sperm production, disruption of sperm maturation and/or function, and interruption of sperm transport. An exogenous testosterone supplement will be an integral part of any hormonal male contraceptive to maintain extratesticular secondary sexual functions such as sex drive, potency, and other androgenic-dependent metabolic functions. Until the long-term safety of testosterone administration is documented, however, an alternative regimen in which the primary suppressive agent is non-androgenic should be considered. A key obstacle is the lack of reliable data on the level of sperm production to which a normal man must be suppressed to offer effective contraceptive protection. Moreover, significant population differences have been found in the extent of sex steroid-induced spermatogenesis suppression required to achieve azoospermia within 6 months of treatment. The increase in contraceptive prevalence precipitated by the introduction of a new systemic male method could be key to averting demographic catastrophe.