China study links tight underwear to reduced sperm quality

A large-scale study conducted by researchers at the University of Science and Technology of China has found a correlation between wearing tight underwear and diminished male reproductive health. Published in the Asian Journal of Andrology, the research analyzed data from 26,836 men seeking fertility assessments.

Comparing 21,221 men who wore loose clothing, such as boxers, to 5,615 men wearing tight garments, including briefs, thongs, or Y-fronts, researchers identified several significant differences. Men wearing tight underwear showed an 18 percent higher probability of lower semen volume and a 12 percent higher probability of reduced sperm motility. Furthermore, there was a 48 percent higher likelihood of abnormal sperm shape and a 108 percent increase in the probability of elevated sperm DNA fragmentation.

A secondary analysis also suggested a higher prevalence of erectile dysfunction and premature ejaculation among the group wearing tight-fitting underwear. Researchers, led by urologist Xue-Chun Hu, suggest that scrotal thermal stress may be a contributing factor, as sperm development requires temperatures slightly lower than core body temperature. While the study identifies these associations, researchers noted it does not definitively prove causation.