out that American men can already buy testosterone gels that could form part of a male contraceptive, and which show how to get a male hormone product approved. Adverts everywhere in the USA talk about "low-T" – low testosterone levels – and the gels men can rub into their skin to treat them. Similarly, NICHD funds researchers at the University of California, Los Angeles and the University of Washington to do clinical trials using testosterone and progestogen in gels.

NICHD is also closing in on an elusive pill-form male hormonal contraceptive. Forms of testosterone that we can absorb from our stomach and gut rapidly break down in the body, meaning men would have to take pills three times a day. "Would men take a pill?" Blithe asks. "We thinkstops men releasing semen and the sperm it contains. He stresses that otherwise the normal physical processes involved in a man's orgasm are unaffected.

"The movement of semen from the testes to where it stays until you have the projectile phase of emission, called ejaculation, happens long before climax," Amobi says. "As soon as you're aroused, spermatic fluid is moved towards the seminal vesicles and prostate. Our pill stops that initial movement by inactivating the tubes that propel fluid from the testes to the prostate."

Amobi and his fellow researchers started from two existing drugs that had caused dry orgasms as an undesirable side-effect. They redesigned the drugs to remove the original intended actions and focus on this. Animal tests suggest that they have succeeded. "We used rams because rats