I was taught that a man's testes are outside his body because sperm can't handle inside-body temperature.

I was thinking there are other times where a man's testes heat up. Like in a bath or spa or sauna. So my question is, can something like a hot bath or a day at the spa decrease a man's fertility?

2 Answers 2


Closely Related to: What is the latest evidence on underwear affecting sperm count?

Elevated temperatures are thought to decrease sperm counts in males.

Elevated temperatures impair sperm production and function. Although studies are limited and are inconclusive, frequent use of saunas or hot tubs may temporarily impair your sperm count.

Sitting for long periods, wearing tight clothing or working on a laptop computer for long stretches of time also may increase the temperature in your scrotum and may slightly reduce sperm production.


Keep your scrotum cool, because heat slows down the making of sperm. To do this, avoid hot baths, wear boxers instead of briefs, and try not to wear tight pants.


Researchers have found that the reason why a man's testicles rest outside the body in the scrotum rather than in the abdomen like the ovaries is because the ideal temperature for sperm production is three to four degrees below normal body temperature. Any warmer will affect sperm count, slashing it by about 40 percent per one-degree rise. Temporary overheating of the testicles can result from exposure to things such as saunas, hot tubs, heating blankets, even waterbeds.

So opinions vary on the accountability of research, but are consistent with heat having a possible risk.


From "Can Male Fertility Be Improved Prior to Assisted Reproduction through The Control of Uncommonly Considered Factors?" (2013):

Hot baths

Jung and Schuppe (26) reviewed the evidence on scrotal temperature and fertility. Studies that addressed professional exposure to high temperatures delivered conflicting results concerning fertility parameters. However, contraception via genital heat stress has been demonstrated using hot sitting baths or insulating suspensors. In a small study, wet heat exposure was a potentially reversible cause of low semen quality in infertile men, and scrotal cooling was found efficient in improving semen quality (27).

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