CLAIM: 

Wearing a tight underwear lowers a man’s sperm count

FACT: 

True. However, its link to infertility remains uncertain

A post by the handle @Men_Sex_Health, shared on the X  platform warns people against wearing tight underwear, saying it would reduce their sperm count by up to 40%.

“Stop wearing tight underwear: Wearing underwear increases the temperature down there. Increasing the temperature by one degree Celsius reduces sperm concentration by 40%,” reads the post that has . garnered 52.4K views, 893 likes, and 104 views.

Stop wearing tight underwear:

Wearing underwear increases the temperature down there.

Increasing the temperature by one degree Celsius reduces sperm concentration by 40%.

— Men's Sexual Health (@Men_Sex_Health) October 18, 2023

However, the handle does not reference any scientific evidence or authority to support its claim.

What is the fact?

Studies have consistently shown that sperm production is most efficient at temperatures slightly lower than the body’s core temperature, a fact that explains the anatomical placement of the testes outside the body. Research suggests that wearing tight underwear can raise the temperature of the testicles, potentially impacting sperm quality and production, though its direct link to infertility remains uncertain.

The production of sperms “is more efficient at a temperature somewhat less than the core body temperature,” according to a report published in Sciencedirect. This is the reason that in mammals the testes are located outside the body. 

When the temperature needs to be lowered, the cremaster muscle (the muscle that hold the testicles in place) relaxes and the testicles are lowered away from the body and are able to cool.

Wearing tight underpants draws the testicles closer to the body, exposes them to higher temperatures. The increase can be anywhere from 0.5 to 0.8 degrees Celsius. But, whether this increase in temperature is enough to destroy the sperm and cause infertility is not clear. 

“The real question is whether this (wearing tight underwear) is enough heating to actually cause infertility, and sadly it’s not one we have an answer to yet,” says a report published in Mcgill in mcgill.ca, a Mcgill University website. 

Studies have found that lifestyle and environmental factors impact a man’s sperm count, impacting his fertility. 

“Several studies have investigated associations between semen quality and the presence of lifestyle stressors i.e. occupational, life events (war, earthquake, etc.) or couple infertility; overall, these studies provide evidence that semen quality is impaired by psychological stress,” says this report.

However, the study does point out that the type of underwear a man wears impacts semen quality.

“The type of clothing a man chooses to wear, may have effects on reproductive health i.e. tight fitting underwear and pants showed a relative risk of 2.5 of having impaired semen quality,” the study mentions. “Thus, it has been suggested that tight fitting versus loose fitting underwear is detrimental on sperm parameters.”

Also read: FACT CHECK: Does using a laptop on lap affect male fertility? - First Check