Scientists have developed a male contraceptive which was 100% effective and side-effect free in trials.
Part of the treatment is given by injection
The hormonal treatment is a combination of an implant under the skin and injections - meaning men do not have to remember to take a pill every day.
Researchers from the Anzac Research Institute, Sydney, Australia, gave the treatment to a relatively small sample of 55 men for a year - and none of their partners became pregnant.
However, it will be some time before the treatment is widely available.
The treatment is a combination of an implant containing the male sex hormone testosterone, which was replaced every four months, and a three-monthly injection of a progestin, a hormone used in female contraceptive pills.
The reversible treatment works by making use of the body's own natural system which is involved in initiating puberty.
The combination of the two hormones temporarily turns off the normal signals from the brain that stimulate sperm production.
But the process also turns off the man's own testosterone production - so he needs to be given extra doses of the hormone to keep him healthy and maintain his sex drive.
In the study, none of the couples used any other form of contraception, and no serious side effects were seen.
Once the treatment was stopped, normal fertility levels returned within a few months.
Professor David Handelsman, who led the research, said: "This is the first time a reversible male contraceptive that will suppress sperm production reliably and reversibly has been fully tested by couples.
"This shows the way for a final product to be a single injection containing testosterone and a progestin which will easily be given by local doctors on a three-four monthly basis and still maintain male sexual health.
'IT WAS MY TURN'
Chris Hains, a Sydney policeman, is now the proud father of baby Connor.
But before he and his wife decided to start a family, they took part in the trial of the male contraceptive.
He said: "My wife Nicole was having problems on the female contraceptive pill so the doctor suggested she came off all contraceptive medication.
"It was an opportunity for me to take part in the trial, and take on the burden of contraception."
Around seven months after Chris stopped having the contraceptive injections, Mrs Hains became pregnant with their son Connor, who is now four months old.
He said it was now up to pharmaceutical companies to develop their research into a usable drug.
Longer and larger trials were also needed, he said.
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.
Dr Richard Anderson, a specialist in reproductive medicine at the Medical Research Unit Human Reproduction Sciences Unit in Edinburgh, said: "It's a very significant step forward.
"Nobody else has done real efficacy studies for a long time - and at the end of the day, that's what you need to do."
"How soon it is available depends on how much the pharmaceutical companies are going to become involved.
"Once they start developing a product, it could be available in just a few years
Liz Davies, of Marie Stopes International, told the BBC: "We welcome any advance in contraception, and particularly those that broaden the options for men to take responsibility."
She said women were likely to feel able to trust their partners to have infrequent injections.
"Whether they would have confidence in a man having a pill every day is another thing."
The research is published in the Journal of Clinical Endocrinology and Metabolism.