I have heard/read conflicting information on underwear and sperm count for men. My girlfriend and I are trying to get pregnant. I often go without underwear since I find that to be the most comfortable but I don't know if this is ideal for sperm count. I've also heard that underwear that is too tight can also be less than ideal. So what is the latest thinking on underwear for men for a high(er) sperm count?
WebMD.com has some insight into this, and based on their report wearing loose light underwear wouldn't have as much effect on your sperm count.
Keep your scrotum cool, because heat slows down the making of sperm. To do this, avoid hot baths, wear boxers instead of briefs, and try not to wear tight pants.
And mayoclinic. com agrees with the above statements, but also state that studies are limited and inconclusive.
Elevated temperatures impair sperm production and function. Although studies are limited and are inconclusive, frequent use of saunas or hot tubs might temporarily impair sperm count. Sitting for long periods, wearing tight clothing or working on a laptop computer for long stretches of time also might increase the temperature in your scrotum and slightly reduce sperm production.
I don't know exactly what you read and reputable it is, but all the sites I am listing from are mostly good references.
There is also this study from 1990 that somewhat supports the above belief: Fit of underwear and male spermatogenesis: a pilot investigation
And another article from WebMD: Boxers vs. Briefs: Increasing Sperm Count also agrees with the above content.
Another study from NCBI.