When you hear two different stories, which do you believe? Well that depends. Typically, we use 4 kinds of information to help us to decide what to think: intuition (gut feeling), source authority, logic and evidence. Now the story: Boxers are better than briefs for your fertility. Believe it?
Intuition and logic suggest that the looser the brief, the more natural the hang and therefore the healthier the jewels. But what does evidence and authority add to that?
Genital Shell Game
One of the best papers published on this topic was done by urologists and was a physiology study that measured scrotal temperatures (considered the source of evil for fertility when raised) in infertile men wearing boxers or briefs. Some men also switched from one underwear type to the other. There was no difference in scrotal temperatures (taken from 3 areas!) in men wearing boxers or briefs, even when they switched underwear types. Granted fertility was not measured, but this clearly showed that scrotal temperature does not correlate with underwear type. Wear what you will if you believe this.
Feeling the Heat
More recently, a study was published by Harvard epidemiologists that was more of a statistical play on the topic. A large cohort of infertile men (n=656) were asked about what kind of underwear that they wear (53% boxers) and their sperm counts and reproductive hormones were examined. Overall men wearing boxers had sperm counts that were 25% higher than those wearing briefs, bikini’s and jockey shorts and their hormones were more normal as well. This would suggest that boxers are better than briefs for fertility, except that all men in the study were already infertile.
One thing that statistical studies can do pretty well is to consider other factors that influence the findings, including a man’s body mass index, level physical activity, and hot bath use. Alas, though it cannot account for other biological factors such as varicoceles (40% of infertile men), the use of other tight-fitting clothes, fevers, flu’s, or the fairly significant day-to-day and season-to-season variation in semen quality that can occur naturally. Nope, statistics can’t assess all of biology and are unable to determine “cause and effect” relationships.
Bottom line is that actual fertility is really the only outcome that matters here and neither study examined this issue. So, based upon the best evidence, to the 70% of U.S. men wearing briefs out there (majority in white), it looks like you’re in no real danger. No need to change your underwear style, but please do change your underwear!