Men who are overweight are more likely to experience fertility problems, experts have claimed.
Research has revealed that obesity increases the risk of a man needing infertility treatment by more than a third.
A study involving more than 25,000 couples found that men who are clinically obese are 36 per cent more likely to be infertile than those of normal weight, while men who are overweight are 20 per cent more likely to be infertile.
With more than a fifth of British men considered to be obese, this trend, reported in the Journal of Human Reproduction, could greatly increase the number of men resorting to infertility treatment in order to father a child.
The researchers, from the National Institutes of Health, claimed: "Increased adiposity (fat) could produce biologic changes in men that reduce their fertility.
"If such changes occur, and are reversible, weight loss may improve their chances of conception."
Meanwhile, a leaked government report detailing a study by experts at Oxford University has revealed that half of Britain's young boys could be dangerously overweight by 2050.