"And you can identify problems with the man in about half of the couples and in about a third, it's exclusively the man". Chavarro said, however, that the analyses show that the rate wasn't much higher. This proven link between temperature and fertility is often the linchpin of pro-boxer arguments presented during debates with briefs wearers.
Researchers at Havard University found that men who wore boxers had a 25 per cent higher sperm concentration and a 17 per cent greater sperm count than men wearing different forms of underwear, reports New Scientist.
In addition, analysis of blood samples collected from 304 of the study participants showed that men who wore boxers had 14 percent lower levels of follicle stimulating hormone (FSH) compared with men who didn't wear boxers.
Both men who wore boxers and men who wore tighter underwear had average sperm concentrations that were "normal"; that is, they had at least 15 million sperm per milliliter of semen.
"We set out to take a deep, broad look at the effect of self-reported underwear choice on sperm", he said. "We're talking in the neighborhood of about 20 million sperm difference", he said. FSH is the hormone that stimulates the testes to produce sperm.
In order to improve your sperm production, you can try wearing loser underwear for improving your sperm production.
Elevated scrotal temperatures are known to negatively affect testicular function. That's the main reason they reside outside the abdominal cavity. The rest wore tighter underwear.
However, researchers noted that none of the sperm counts measured were below the normal range, implying that underwear is not a major factor in pregnancy. In 1998, a small study consisting of 97 men was published in the Journal of Urology, where the authors claimed that the hyperthermic effect of brief style underwear had been exaggerated, and concluded that routinely advising infertility patients to wear boxer shorts was not justified.
Other lifestyle activities of these men were also seen.
Men trying to get their partners pregnant may not have to throw out all their briefs, said Dr. Harry Fisch, a clinical professor of urology and reproductive medicine at the Weill Cornell Medical College in New York City.
However, other experts said they wouldn't make a flat-out recommendation for men to switch to boxers. "But if you're exercising and wearing tighter underwear, you're probably putting your testicles at risk for heat". "There is a big difference between measuring aspects of sperm quality (as done in this study) and measuring fertility". "It's lower in hotter seasons".
Which makes us think: who are all these dudes going around getting Jacuzzis?
The study found underwear choice could actually be a "key regulator" of sexual development and reproduction.