It is the oldest piece of fertility advice going: wear loose boxers. Is there anything to it, or is it a myth? The answer: there is something to it, it is a small lever, and it is the easiest change on the entire list.
What the research found
Studies comparing men by underwear style have found that those who wore looser styles like boxers tended to have higher sperm concentration than men in tight, close-fitting briefs. The reason is the familiar one: tight, insulating underwear holds the testicles closer to the body and warmer, and your testicles work best a few degrees below core temperature.
How much does it matter?
Be honest about scale: underwear is a modest factor, not a magic switch. It is unlikely to be the deciding issue on its own. But it costs nothing, it is effortless, and small heat reductions add up alongside the bigger ones like hot baths and saunas.
The simple move
- Favour looser, breathable underwear, especially if you run hot or sit all day.
- Combine it with the bigger heat levers; no single change does it alone.
- If heat is a constant in your life, cooling is the backstop. Full guide here.
This is general information, not medical advice. For a real concern, get a semen analysis and talk to a doctor.