Tighter underwear could potentially lead to higher testicular temperatures, by holding the testicles closer to the body, but studies looking at the effect of underwear style on testicular function have had inconsistent results.
"This study does not necessarily suggest that men should alter their clothing preferences and tendencies; the study was conducted among men in an infertility clinic and the results may not be generalizable to men in the general population", she said.
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The debate over whether boxers or briefs are better for men's fertility may finally be settled.
"The men who may benefit most from paying attention to what type of underwear they're wearing are men who are already having problems with fertility", he said.
The study probed the potency of 656 men between 32 and 39 and found that guys who sported boxer shorts had a 25 percent higher concentration of sperm and 17 percent higher sperm count totals.
"Because of this, we were able to find a potential compensatory mechanism whereby decreased sperm production relating to the type of underwear signals to the hypothalamus to increase secretion of gonadotropin [s], [hormones that act] on the testes and that is reflected by the increased levels of FSH, to try to increase sperm production".
The biggest difference in sperm concentration between men wearing boxers and men wearing snugger jockeys and briefs, researchers said.
Your underwear choices might also affect the quality of your sperms.
The groundbreaking study is the largest of its kind to look into the truth of a long-held suspicion that tighter trousers such as Y-fronts or briefs affect a man's ability to father children. The researchers took self-reported information on the type of underwear worn by the subjects through a take-home questionnaire.
Previous research has linked increased scrotal temperatures (yes, that does mean "hot balls") to declining testicular function and lower quality sperm, so researchers wanted to see if the style of underwear a man wears might have an effect.
"If you're just walking along in an air conditioned room, it's probably not going to make much difference between boxers and briefs", said Fisch, who was not involved in the study.
'I would also question the use of underwear type as a scientific way of measuring scrotal heat.