Underwear. Why do we even bother putting it on in the first place? You can thank your ancestors from way back in the day, a.k.a. centuries ago. They decided it would be best for their intimate areas not to touch their precious outer garments.

The “they” refers to the men of the time who invented and wore something called braies in the Middle Ages. Women didn’t get in their knickers until the 19th century. They were left hanging with something called a shift or a piece of long linen. Before that, ladies were left to lace-up corsets consisting of the ever-so-comfy and fashionable whalebone. (Sounds practical, right?)

Your urologist wants to talk to today’s more “modern” man. Your choices for undergarments are not as diverse as your female counterpart, but you still have options. If you’ve ever been ready to start a family, you might know where we’re going with this. There was talk a couple of years ago, following the release of a study in the Human Reproduction journal where the findings of our nation’s beloved tighty whities weren’t so bright.

Is Too Tight Trouble?

To gather data for the study, Dr. Jorge Chavarro, along with colleagues at Harvard University, asked 656 for both blood and urine samples. They also were asked (you guessed it) what kind of underpants they prefer.

As it turns out, guys who choose boxers over briefs had a 25 percent higher sperm concentration and a 17 percent higher total sperm count. They also showed 33 percent more swimming sperm in a single ejaculate compared to men who like other, more constrictive underwear.

Turn Down the Heat

Is tighter underwear bad for baby-making? Some doctors and researchers say other factors such as age, smoking history, weight, diet, lifestyle, etc., could also play a role in a man’s reproductive health. So, your urologist will probably say you can’t just blame everything on tighty whities.

However, there’s also plenty of evidence that sperm production requires just the right temperature, and it’s definitely sensitive to heat. This makes sense seeing as how male mammals have scrotum to house the testes or the organs that work hard to produce sperm. Because we’re warm-blooded, the scrotum is thought to help keep this area slightly chilled from our normal body heat. This is where the issue lies with tight underwear that hugs the body. They tend to push things inward, closer to your body, causing temperatures to rise and the potential for sperm counts to slump.

Should You Care About Your Underwear?

So, while there’s evidence that tight underwear can reduce sperm production, it doesn’t seem to affect overall fertility — even people in the study who had reduced sperm counts tested within a normal range. The bottom line is this: If you’re looking to start a family and know your sperm numbers are low, it might be a good idea to switch to some boxer briefs. It’s one of the more cost-effective ways to potentially boost your baby-making efforts.