A new study published in the journal Human Reproduction found that men who wear loose fitting underwear have better sperm counts and motility compared to men who wear tight fitting underwear.
Researchers from Harvard looked at the semen analyses of 656 male partners of couples seeking fertility treatment. The men were all between 32 and 39 years old. The type of underwear worn by those men was collected from a take-home questionnaire.
About half of the men studied reported usually wearing boxers. Those men were found to have 25 percent higher sperm concentration, 17 percent higher total sperm count, 33 percent higher total motile sperm count, and 14 percent lower serum FSH levels compared to men who reported wearing briefs. Men who wore boxers also tended to have a higher percentage of motile sperm and a higher morphologically normal sperm count compared to men who wore briefs.
This study confirms what we already suspected about how underwear choices may affect male reproductive function. Tighter fitting underwear can cause an increase in scrotal temperatures, which is likely the cause of the lower sperm count and motility in the group of men who most often wore briefs.
This study is also in line with a 2015 study from Stanford University, which showed that men who wear boxers during the day and slept without underwear at night had 25 percent lower rates of damaged DNA in their sperm compared to men who wore briefs during the day and night.
If you are struggling with infertility, you may want to ask your doctor to order a semen analysis. While underwear choices don’t necessarily affect fertility for all men, if your semen analysis is abnormal, this is one easy lifestyle factor that can be changed.
For more information on how lifestyle choices can affect fertility for both men and women, visit our Lifestyle and Fertility page.