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.
Men fond of wearing tight underwear who are now trying to conceive a child might want to think again following a new study.
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Each participant also answered a questionnaire about the style of underwear they wore most frequently in the preceding three months. 345 men said that they liked boxer shorts, while 311 said that they wore tight underwear. "Men could improve their sperm production by easily changing their type of underwear worn to boxers".
Men who wore boxer shorts had 25 percent higher sperm concentration than those who wore briefs, researchers found.
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"It might be predicted that men who spend much of their day seated and also wear tight underwear would be most likely to suffer a fall in their sperm production due to scrotal heating", Prof Sharpe said.
That finding suggests that, in men who wear tighter underwear, decreased sperm production may send a signal to the brain to increase levels of FSH to compensate for the lower sperm production.
"Our study provides evidence that a seemingly random lifestyle choice could have profound impacts on hormone production at the level of the testis and the brain", Jorge Chavarro, an associate professor at the Harvard T C Chan School of Public Health who led the study said in a press release.
When in comes to male fertility, it seems the old "brief versus boxers" debate has finally been settled. Their sperm were 33 percent more motile.
The new study is one of the largest to examine the link between underwear type and sperm quality. Higher levels of FSH indicate that the body is pushing the testes to produce more sperm as counts are low. And the authors acknowledge that they lacked information about other factors, like the men's preferred trousers styles and materials, that might influence the results.
The study has still not demonstrated a clear correlation between the type of underwear and sperm count/quality and whether all these sperms translate into pregnancy.
"Since men can modify the type of underwear they choose to wear, these results may be useful to improve men's testicular function".
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