https://www.hsph.harvard.edu/news/press-releases/does-underwear-style-affect-sperm-production/
Among the study participants, 53% reported usually wearing boxers. Analysis of semen samples showed that these men had 25% higher sperm concentrations and 17% higher total sperm counts when compared with men who did not primarily wear boxers. Men who wore boxers also had higher percentages of motile sperm, or sperm that are capable of moving through the female reproductive system and fertilizing an egg.
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