Boxers or briefs: could it affect your sperm?

Male underwear choice. A highly personal decision based on comfort and fit, but does it have an impact on sperm count?

I recently came across a study conducted at a Fertility Clinic in Massachusetts General Hospital which sought to investigate the question of whether underwear choice made a difference to male fertility- more specifically, sperm count and quality. The study can be found here.

This has been a fairly contentious issue in the past- most urologists and fertility specialists seem to think that there isn’t really much evidence either way. But we do know sperm are highly sensitive to heat (which is why the testes are outside the rest of the body!), so you would think the looser-fitting boxers would be more likely to preserve fertility.

Well, this study sheds a little more light on the issue. 656 men filled in a questionnaire identifying their usual choice of underwear (including boxers, jockeys, briefs, or bikini) and tests were done to analyze their sperm and blood hormone levels.

Men who reported wearing boxers majority of the time had a 25% higher sperm concentration, 17% higher sperm count, and 14% lower FSH levels than men who did not. FSH, also known as Follicle Stimulating Hormone, is a hormone released by the pituitary gland in the brain to stimulate the testes to produce more sperm. Hence, FSH levels tend to be inversely related with sperm count. These men also had high levels of motile sperm- or sperm that are better able at navigating the female reproductive tract in order to fertilize an egg, resulting in conception.

The researchers controlled for possible confounding factors- things like sauna use, use of heating blankets, and medical conditions known to impact on sperm production, such as having a undescended testes at birth or a varicocele (a swelling of the veins in the scrotum). This means that the findings are more likely to be real, as they can’t be explained by other factors of the study participants. For example, if they hadn’t controlled for having had a varicocele, for all we know men who have had a varicocele are more likely to wear boxers, so it isn’t the boxers that have caused the results, but the varicocele.

Of course, this was only a cross-sectional study, and primarily based on a questionnaire, which means the data is dependent on the participants being able to recall their underwear use accurately (although I suspect most would be able to do so!). The study was also not able to take into account other possible confounding factors, such as the type of other clothing worn, the fabric of the underwear, etc. Hence, a study like this would not be able to say that briefs definitely cause lower sperm counts, but suggest that perhaps the choice of underwear may impact sperm production.

In any case, for those that are worried, it can’t hurt to give the boxers a bit of a go.

If you are worried about your fertility, you can see me or any other GP for a referral for a sperm analysis, which can take a look at the quantity and quality of your sperm.