It does not seem to have done David Beckham much harm, but wearing tight underwear could damage sperm and harm the chances of having a baby, according to new research.
In fact, men who are hoping to become fathers should ditch their pants altogether at night and sleep naked for the best chance of getting their partner pregnant. In the daytime, a pair of roomy boxer shorts is considered the best garment to keep sperm cool and boost reproductive success.
A study by the National Institute of Child Health and Human Development, Maryland, and Stanford University followed 500 men for up to 12 months, tracking their underwear choices, and monitoring the quality of their sperm.
They found that men who wore boxers during the day and were naked at night had 25 per cent less DNA fragmentation in their sperm compared with men who wore tight briefs day and night.
“Among men in the general population attempting pregnancy type of underwear worn during the day and to bed is associated with semen quality,” said lead author.
“Reducing exposure for bed decreases DNA fragmentation and better quality parameters are observed in men wearing boxers during the day and none in bed.”
In 2012, UK researchers showed that men wearing boxer shorts had better seem quality but this is the first to suggest that going commando at night could improve chances of conception. Other studies have also lauded the benefits of sleeping naked. Women who sleep au natural less likely to suffer from yeast infections.
Men who go commando in between the sheets are not as prone fungal infections in their groin – also known as the Jock Strap Itch. Getting too hot at night is also thought to damage testosterone production.
Almost a third of men choose to sleep naked in Britain compared to a fifth of women.
Leading fertility expert Allan Pacey, professor of andrology at the University of Sheffield, said: “We have known for some time that men who increase the temperature of their testicles, either through the heat exposure at work or by wearing tight underwear, have poorer semen quality compared to men whose testicles are cooler.
“What has never adequately been shown is whether men can improve things by changing the choice of their underwear, but this study – although quite small – goes some way to suggest that is true.
“What we really need to see is whether switching to looser underwear makes their partners get pregnant more often or quicker than they would have done had the men continued to wear tight underwear.
“Having said that, switching underwear is hardly a risky thing to do, so buying some looser pants might be good advice for would be fathers.”
The research was presented at the annual meeting of the American Society for Reproductive Medicine in Baltimore.