Couples across the UK are being recruited to take part in a year-long trial testing a new male contraceptive gel.
The gel called NES/T is applied daily to the shoulders and upper arms, and contains hormones which suppress the amount of sperm produced in the testes.
Trials of the contraceptive are taking place in Manchester and Edinburgh, and couples will be asked to use it as their sole contraceptive for 12 months.
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John Reynolds-Wright, a clinical research fellow from the University of Edinburgh who is helping to conduct the trial, told talkRADIO he hoped the gel would "give men the tools to start looking after their own reproductive health".
"With the oral contraceptive pill we say that’s between 97 and 99 per cent effective because we’ve done this kind of study to tell us that and let us know that. We need to do a similar study for this contraceptive so that we can actually say how effective it is," he said.
"This is a short-acting contraceptive because you need to use it every single day, but we’re hoping it’s the sort of contraception that men might be able to use for years at a time if they wanted to."
The UK is not the only country starting to test out the gel - which has been in the development phase for around 10 years - with sites in Sweden, Italy, Kenya, Chile and the USA all looking for healthy couples to take part in trials.
Female contraceptive pills. Image: Getty
A preliminary trial in the UK showed that the gel suppressed the production of sperm in all the men that took part, but researchers are not sure how this will translate in the larger-scale study.
"If someone became pregnant during the trial they would have all the options open to them," Mr Reynolds-Wright added.
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"They can continue with the pregnancy, they can end the pregnancy if they like. The only thing that would be different is that we would follow them up and work out what had happened afterwards."
Men must be aged between 18 and 50 and be in a stable relationship with a woman aged between 18 and 34 to participate.
Interested parties can apply to participate in the trial by calling 0161 276 3296 (Manchester) or 0131 242 2669 (Edinburgh).