A study published recently in the journal Human Reproduction should be required reading for guys who wear brief-type underwear. The study of 939 men with low sperm counts found that the guys who wore briefs (as opposed to boxers) were more likely to have lower sperm counts. Why would that be? The answer is: heat.
Let’s back up a second for some basic anatomy. Sperm are made in the testicles, which hang from the body in the scrotum. The reason for letting the “family jewels” swing in the wind like this is that the sperm-making Sertoli cells of the testicles don’t work unless they are cooler than body temperature. Warm them up more than a few degrees and for more than a few minutes and sperm production is temporarily shut down.
Briefs keep the testicles snugly against the body, which can warm them slightly, possibly hurting sperm production. Boxers, in contrast, let the testicles hang in a lower, more natural position. Now, clearly a guy’s choice of underwear isn’t the only thing that can hurt fertility—and there are plenty of perfectly fertile guys out there who wear briefs. But if you’re having a hard time getting pregnant, switch to boxers. And avoid romantic interludes in hot tubs, too!