Hugh Pickens writes "BBC reports that recent tests in China indicate a monthly injection of testosterone, that works by temporarily blocking sperm production, could be as effective at preventing pregnancies as the female pill or condoms and could revolutionize birth control. In trials in China only one man in 100 fathered a child while on the injections and six months after stopping the injections the men's sperm counts returned to normal. "Our study shows a male hormonal contraceptive regimen may be a potential, novel and workable alternative," says Lead researcher Dr Yi-Qun Gu, from the National Research Institute for Family Planning in Beijing, China who added that if further tests proved successful the treatment could become widely available in five years from now. Previous attempts to develop an effective and convenient male contraceptive have encountered problems over reliability and side effects, such as mood swings and a lowered sex drive. However despite the injection having no serious side effects, almost a third of the 1,045 men in the two-and-a-half year study did not complete the trials and no reason was given for this. The news was welcomed by family planning experts. "If a male contraceptive like this became available it would be great and would give people another choice," says Laurence Shaw, of the London Bridge Fertility Center. "It would empower men to make a decision which involves more than just a condom. At the moment the onus is on the woman and men do not have that much choice.""