You may have heard that tightie whities hurt your sperm.

The theory is that if underpants hold your scrotum close to your body, it makes your testicles too warm, creating a hostile environment for sperm production.

But any impact your underwear has on your semen is not enough to affect your ability to conceive a child, suggests a new study from the National Institutes of Health.

The researchers looked at 35 aspects of sperm quality for 500 men who wanted to conceive a child. Some aspects of sperm quality were better among men who wore boxers, and some aspects of sperm quality were worse.

All of the differences were so subtle, however, that none of them were statistically significant.

More importantly, the men’s choice of underwear did not affect how long it took them to get their partners pregnant.

Wear whatever underwear you feel most comfortable in, says study coauthor Michael Eisenberg, M.D., an assistant professor of urology at Stanford University Medical Center.

If you want to conceive, the more crucial steps are to reach and maintain a healthy weight, eat well, and exercise regularly, says Dr. Eisenberg.

If you’re having trouble getting pregnant, keep in mind that fertility problems are due to the man about half the time, he says. See your primary doctor or a fertility specialist if you’ve been trying to conceive for 12 months with no luck.