Here’s a quick answer: Yes, tighter underwear may reduce sperm count. That said, it’s unlikely to reduce sperm health enough to cause infertility. In healthy fertile men, even when briefs reduced sperm counts, vital sperm health measurements were still in the normal range.
Why Might Tighter Underwear Harm Sperm Health?
The concern with tight underwear in men is all about heat. Sperm cells are sensitive to rises in temperature. In fact, they are so sensitive to heat that your own body heat is a problem. Have you ever wondered why the testicles sit outside of the body? Considering how important the testicles are for reproduction of the species, having them in a vulnerable position seems risky from an evolutionary perspective. The testicles are held loosely by the scrotum to keep sperm cells further away from a source of heat—your own core temperature. The average scrotal temperature is between 2.5 and 3 degrees Celsius cooler than your body temperature. While the average human body temperature (when not ill) is 37 degrees Celsius, sperm production is most ideal at around 34. Research has found that even changes in room temperature can impact sperm movement. We also know that extended illness with high fever can harm sperm health in men. What does underwear have to do with all this? Since the scrotum intentionally holds the testicles loose and away from the body, it makes sense to wonder what would happen if the testicles were held much closer to the body—which is what happens when a man wears tight underwear.
What the Research Says
A number of studies have looked into whether man’s underwear choices impact sperm count and health. One study included 656 male partners of couples seeking help at a fertility clinic. Researchers ask men to share what style of underwear they wore. Their semen was evaluated, as well as their FSH blood levels. In men, FSH is a hormone that triggers sperm production. Sperm concentration is the amount of sperm cells found in a particular measure of seminal fluid. Researchers also found that FSH levels were higher in the men with lower sperm count and concentration. This may be because the body was reacting to the lower sperm counts by boosting FSH levels, in an effort to boost sperm production. This study, while interesting and important, still doesn’t answer the question most couples want to know which is this—can your underwear reduce fertility enough to cause fertility problems? A separate study looked at 501 couples who were trying to get pregnant. Unlike the study described above, these couples weren’t already having fertility problems. They were just starting to try and get pregnant. The researchers look at the impact underwear choice (comparing boxers, briefs, and boxer-briefs) may have on how long it took for a couple to get pregnant and on the odds of experiencing infertility. This study also looked at whether changing underwear choice had a positive effect on semen health. The study did not find significant differences in semen health based on underwear choice, and underwear choice did not impact how long it took couples to get pregnant nor how frequently couples experienced infertility.
A Word From Verywell
While some studies found that underwear choice can affect sperm health, not all studies have found an impact. If briefs do negatively impact sperm health, this may be more pronounced in men who are already experiencing fertility problem. If you don’t have a known fertility problem, you probably don’t need to worry about which underwear you choose. However, if you already have fertility struggles, switching to boxers—or at least switching to boxers or no underwear at night—may be worth trying. Switching underwear won’t, however, solve a fertility problem. If you love your briefs, don’t feel guilty for continuing to wear them.
