Dr. Jorge Chavarro, lead author of the study and associate professor of nutrition and epidemiology at Harvard, told NBC News their study confirms previous smaller-scale studies.
The men, between the ages of 32 and 39, were surveyed about the style of underwear they had been wearing for the past three months. Thus, it can be inferred that wearing loser boxers can be helpful in improving sperm count, but the tighter ones will not make you infertile either. Those men had 25 percent higher sperm concentrations and 17 percent higher total sperm counts, compared with men who did not, the study found.
He cautioned that there is no definitive proof that switching underwear style would make any difference because there may be other factors behind the link between wearing boxers and increased sperm count.
As part of the study, the men in couples who were seeking fertility treatments were quizzed about their underwear choices and which underwear do they usually prefer. Therefore, to determine the cause of male infertility, you first analyze the amount and concentration of sperm.
A new U.S. study has found that men who wear loose-fitting boxers have a significantly higher sperm count than those who wear other types of underwear.
Wearing skinny jeans or a certain type of underwear fabric could also skew the results, the study says.
Anything that prevents this cooling is likely to impair both sperm output and quality.
"As a society, traditionally, fertility has been thought of as a female issue".
The reason briefs may impact sperm counts is that they keep the testes close to the body, Chavarro said.
While men who wore briefs had millions fewer sperm, that wouldn't be a problem in a man with a normal sperm count, Chavarro said.
The study found underwear choice could actually be a "key regulator" of sexual development and reproduction.
Lidia Mínguez-Alarcón, author and a research scientist at Harvard's T.H. Chan School of Public Health also said that this study provides science behind the recommendation for loose underwear to men who have fertility problems.
The conviction of the scientists reduced levels of this hormone in men who wear boxers, compared to those who have a more narrow trousers, due to the fact that spermiogenesis occurs normally and is not regulated by the high concentration of hormones, which takes effect at the time of damage of the scrotum is too narrow sheets.
There were no significant differences in DNA damage or other reproductive hormones in the underwear groups. Further the levels of their FSH was 14 percent lower. They also answered a questionnaire about their underwear.