Male contraceptive pill hopes after gene discovery Dr Lee Smith, from the university, said if the gene was blocked the testes would continue to produce sperm, only releasing immature, ineffective sperm which had not developed into the final stages. The important thing is that the effects of such a drug would be reversible because Katnal1 only affects sperm cells in the later stages of development, so it would not hinder the early stages of sperm production and the overall ability to produce sperm. If you are a woman, would you trust a man to take the male contraceptive pill? He added it would be "relatively difficult" to do as the protein lives inside cells, but there was "potential" to find another substance that protein worked with as an easier target. The research, funded by the Medical Research Council, was based on altering the genetic code of mice to discover mutations which led to infertility. Researchers at the Centre for Reproductive Health at the University Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, told the BBC there was "certainly a need" for a non-hormonal contraceptive for men and that this had been a "Holy Grail" of research for many years. "The gene described by the research group in Edinburgh sounds like an exciting new possible target for a new male contraceptive, but it may also shed light on why some men and sub-fertile and why their sperm does not work properly," he said.