Exposing the Truth: Men’s Undies and Fertility

Are you a guy who favours white Y-fronts, silky boxers, or Lycra trunks? Did you know your underwear of choice can actually affect your fertility?


There are numerous urban myths relating to a guy’s underwear of choice, and its implications for the sex of any babies he fathers. One popular story, believed by many, is that wearing tight undies will result in a baby boy, whereas looser garments will give the happy couple a baby girl. If only it was that simple!

Scientists and researchers have debunked this myth – let’s face it, in certain cultures, every man would be wearing the tightest briefs possible to ensure a long line of sons – and sons there would be, if it in fact worked. We know this is simply not the case.

There is, however, some truth to the idea that the style of underwear worn can impact on a man’s overall fertility.

A man’s testicles hang outside the pelvis for a reason – and it can’t be denied that inside the pelvis would be a safer environment. But optimal temperature is imperative for sperm production – it must be lower than the core body temperature – and at warmer temperatures, sperm counts diminish. Some researchers have found evidence to suggest that tight underwear, which holds the testes close to the body, particularly in warm weather, can be detrimental to a man’s sperm count (and consequently, his fertility).

Low sperm count is the cause of infertility in half of couples who struggle to conceive.

The effects of overheating the testicles are, fortunately, temporary, lasting from three to eleven weeks.  Additionally, there is some suggestion by scientists that polyester underwear also reduces sperm production, as this fabric creates electrostatic friction.

Some people have pondered this quandary to the extreme. There is even one company who has patented cooling boxers with the specific purpose of cooling the scrotum: organic cotton shorts with an ergonomic gel cold pack to insert into the undies. Wearers are “strongly advised “not to wear them for more than an hour at a time.

So what is the answer? Ideally, when trying to conceive, wear loose, cotton underwear. It needn’t be boxers, necessarily; gentle support is still important, particularly when exercising or playing sports. The key is to wear undies that aren’t too tight or restrictive, but are comfortable and allow a little “hang”. At the same time, don’t sit in hot spas, saunas, or baths, and don’t wear those tight skinny jeans. And don’t wear underwear to bed.