Reproductive equality: a male pill?

If men got pregnant, stores would be bursting with contraceptives, some women say. Researchers in the United States and Italy would like to turn this witticism in a practical direction. If their experiments succeed, drugstores may one day be stocked with a new birth control pill-for men. Only two male contraceptives are currently available, vasectomy and the condom. Vasectomy has two drawbacks: The lag between surgery and sperm depletion can result in unintended pregnancy, and the procedure can be reversed only with great difficulty. Also imperfect, condoms can break, men may use them incorrectly, and some men resist using them.

Now, in what he believes is the first clinical trial of an oral contraceptive for men, William J. Bremner of the University of Washington in Seattle and his colleagues in Bologna, Italy, say they have proven such a pill can work. The research team gave eight Italian men two hormone pills twice daily for 16 weeks. Each pill contained one of two hormones, testosterone undecanoate or cyproterone acetate.

The researchers released preliminary results on four of the men at the 10th International Congress of Endocrinology in San Francisco on June 12. Sperm counts for three of them fell by roughly a factor of 10, to 3 million or fewer sperm per milliliter of seminal fluid. Concentrations this low meet the World Health Organization (WHO) definition of infertility.

In earlier studies, conducted by WHO, weekly injections of hormones were found to lower sperm counts in 65 percent of Caucasian men and more than 90 percent of Asian men. This injectable contraceptive produced a failure rate of just 1 percent in men whose sperm counts were 3 million or less, Bremner says. Men with higher counts had failure rates of 3 to 4 percent-comparable to the rate of the female pill.

Bremner cautions that the male pills didn't work in all eight cases. "There were some men whose sperm counts were not fully suppressed . . . which means that the agents and dosages we administered were not optimal." Yet the study has shown that "it is possible to get sperm suppression with oral agents," Bremner asserts. He says his group plans to try other hormones and dosages to bolster effectiveness.

"If it really works, that's potentially exciting," says Barry Zirkin, head of reproductive biology at the Johns Hopkins School of Hygiene and Public Health in Baltimore.