Male hormonal contraception: an update on research progress.

New male contraceptive options are needed to provide couples with additional well-tolerated, effective, and reversible contraceptive choices. Research and development of new male hormonal contraceptives have produced many exciting possibilities over the past 20 years. Two large, multicenter, World Health Organization (WHO) trials demonstrated that high-dosage testosterone provides effective suppression of follicle-stimulating hormone, luteinizing hormone, and spermatogenesis. In men whose sperm counts suppress to < or = 3 million/ml, high-dosage testosterone provides contraceptive efficacy similar to female oral contraceptives. Since the WHO efficacy studies, investigators have focused on evaluating combination regimens that include lower dosages of testosterone plus gonadotropin-releasing hormone (GnRH) analogs or progestogens (progestins). In small, randomized trials, combination regimens of testosterone plus GnRH analogs or progestogens have produced more uniform suppression of spermatogenesis than high dosage testosterone alone. The major adverse effects of most of the studied male hormonal contraceptives are modest bodyweight gain and suppression of high density lipoprotein-cholesterol levels. The latest research studies indicate that a well-tolerated, effective male hormonal contraceptive may soon be developed.