Does underwear really affect men's fertility?

Key Points:

• A new large-scale study of 27,000 men by Chinese researchers found that wearing tight underwear is linked to poorer semen quality, higher DNA damage in sperm, and increased prevalence of erectile dysfunction and premature ejaculation.
• The study suggests that tight underwear raises scrotal temperature by 0.5°C to 1°C, which can negatively impact sperm production and sexual function, as optimal testicular temperature is slightly cooler than core body temperature.
• Previous research, including a 2018 Harvard study, indicated that men wearing boxers had higher sperm concentration and count, but findings on sperm quality and fertility outcomes have been inconsistent across different studies.
• Some recent studies and reviews have found no significant difference in fertility or pregnancy outcomes based on underwear type, suggesting that underwear choice alone may not meaningfully affect male fertility.
• Researchers recommend choosing looser, breathable underwear to potentially protect semen quality and sexual health, though other factors like fabric and pants type may also influence testicular temperature and reproductive health.