A scientific breakthrough could finally bring a male contraceptive pill into reality.
A temporary 'vasectomy', which stops sperm in its tracks without the need for surgery, is finally on the cards after years of research.
Previous attempts to develop a male pill have sought either to alter a man’s hormones or to make his sperm ineffective.
But the new technique simply stops sperm leaving the body during sex - which scientists say will reduce men’s concerns about long-term virility and libido that have been associated with other approaches.
It is also likely to appeal to women uneasy about the female pill’s potential to raise the risk of heart attacks, stokes and blood clots.
Dr Sabatino Ventura, whose team at the Monash University in Australia published the findings, said the new technique works by simply blocking two proteins involved in the ejaculation process.
By using medication to target the mechanism by which sperm leaves the body, rather than attempting to alter a man’s hormones or kill his sperm, Dr Ventura said the potential side effects for men would be vastly reduced.
Significantly, the technique would not affect a man’s sex drive, and fertility could be switched back on simply by not taking the pill.
Dr Ventura said: ‘Most of the previous strategies to make a male contraceptive have either been hormonal strategies, which would produce a lot of sexual side effects or effects on masculinity, neither of which men would like, or they would make sperm dysfunctional, which is difficult and might produce long-term effects on offspring.
‘Using our strategy we avoid all those problems, which is why it is so significant.’ Taken daily, a male pill would allow couples to share the burden of family planning.
In the past 50 years there have been few changes in male contraception compared with the range of options available to women.
Although several male pills are in development, the only contraceptive methods available to men today are condoms or a permanent surgical vasectomy.
The new technique, which is detailed in a paper published in the Proceedings of the National Academy of Sciences, has been shown to work in mice through genetic modification.
The male mice were 100 per cent infertile after two proteins were deleted from their bodies.
Crucially, the sperm retained in their body was undamaged and was later used via IVF to produce healthy babies.
In humans the same process would work by using medication to disrupt the same two proteins, blocking a message from the brain which moves sperm into the penis.
The man would still ejaculate but - as with a vasectomy - there would be no sperm.
Dr Ventura said: ‘We disrupted two proteins in the muscle cells which have to contract to move the sperm from the storage site to the base of the urethra.
‘When the brain sends its message to the testicular organ for the muscle to contract, it doesn’t get that message.’ Trials will now start to develop the medication and put it through clinical trials, a process which could take as little as ten years.
But women may not be so sure.In a 2011 survey carried out by researchers at Anglia Ruskin University, half of women said they would not rely on a male pill as contraception - because they did not trust their partners to remember to take it.
Lynn Hearton, of sexual health charity the Family Planning Association, said: ‘We welcome any research that has the potential to broaden contraceptive choices for men and women.