Does a Hot Bath Affect Male Fertility?

Hot baths, hot tubs, and saunas are soothing places to relax, especially after a long physical day. However, for men, prolonged exposure to these wet hot conditions can have a detrimental impact on fertility and semen quality.

When it comes to trying to conceive, fertility concerns are not just a female issue. In fact, of the one in every six couples who are struggling with infertility, at least half of all cases male fertility issues is a major or contributing cause. Simplified, approximately 10 percent of all males in the United States who are trying to conceive, struggle with infertility. When it comes to correcting these male factor infertility issues healthy sperm and healthy testosterone levels are key, and both can be negatively impacted by hot temperatures involved with these means of relaxation.

Correlation Between Semen and Scrotal Temperature

It’s an undisputed fact that when it comes to male anatomy, the testicles are vulnerable and exposed on the outside of the body, and this placement is for a very specific reason. For adequate testosterone production, which occurs in the testes, and optimal sperm development to occur, the scrotum and thus testes, are required to be two to seven degrees cooler than the body’s core temperature. If the testicles are too warm, they have a lower chance of producing healthy sperm in testicle and will not mature normally.

Not only have researchers found that raised scrotal temperatures negatively impact sperm production, they have also found that heat exposure decreases semen parameters in both humans and animals.

Natural Temperature Regulation with Male Anatomy

Because of this anatomical need for cooler temperatures, the body has advanced biological functions that work to keep the scrotal temperature at optimal levels.

While the human body is capable of withstanding most temperature changes that arise due to exercise and normal weather patterns, as the ambient temperature rises by one-degree, scrotal temperature works to regulate itself by increasing by only one tenth of a degree. To accomplish this temperature regulation, the testes are protected by the cremaster muscles, which involuntarily relax or contract to draw the testes closer to the body for warmth or away from the body for cooling. This means that male testicles maintain a temperature of 95 degrees (35 C), which is two degrees lower than average body temperature.

Still, despite these mechanisms in play, the testicles are vulnerable to excessive heat, and can only regulate temperatures for so long. Even just a few degrees of scrotal temperature increase are enough to inhibit spermatogenesis, affect male fertility and even result in infertility.

The Effects of Heat on Male Fertility

Many doctors have advised men having trouble conceiving not to indulge in hot baths or hot tubs. This recommendation is founded on the knowledge that prolonged exposure to hot, wet environments may worsen sperm conditions. After working to confirm this link in studies, researchers discovered a surprising finding. Not only does continuous heat exposure reduce sperm production or create abnormally shaped sperm cells, but sperm cells can actually die when they come into contact with too much heat, ultimately resulting in infertility.

Several experimental studies show that an induced spike in the testicle temperature or the scrotum, the sac containing the testes, reduces sperm quality and count. In further research, a study examined eleven men who spent at least thirty minutes weekly in hot baths or tubs. Within three months after stopping exposure to these sources of heat, five out of eleven patients had an almost 500 percent increase in motile sperm counts.

Additionally, a 2015 study showed elevated temperatures decreased sperm concentration and movement by about half, and studies have continued to suggest that using saunas and hot tubs regularly can negatively affect sperm.

In 2016, researchers found that soaking the testicles in hot water for 30 minutes damaged sperm DNA and reduced sperm production.

Two other studies, one conducted in 2020 in a study of 1,311 men, and one study conducted in 2013, looked at sauna use specifically, and found that twice a week exposure for three months can cause an increase in scrotal temperature that reduces sperm concentration and motility significantly and alters sperm DNA. The good news is that after six months of stopping sauna use, sperm production returned to normal.

According to another study from as far back as 1983, just 20 minutes in a sauna can affect sperm production. According to the study, sperm counts dropped after one week, before returning to the same level after five weeks of avoiding exposure. In this study, sperm motility issues increased after sauna treatment, as did the number of immature sperms, proving that sperm dysfunction and production as a result of higher temperatures is nothing new.

The studies conclude that due to this correlation, it is recommended that infertile men change their lifestyle choices related to infertility.

Reversing Heat-Related Sperm Quantity Decline

While hot tubs, baths, and saunas do negatively impact sperm, studies show that their effects are generally temporary, as the quality of sperm usually returns to normal within a few months of stopping heat exposure. Therefore, men who are struggling to conceive with a partner can improve their semen quality by limiting hot water exposure.

It is also important for men suffering from already low sperm counts or slow movements in semen, avoid exposure to heat, whether through hot tubs and saunas or other activities, to better improve sperm health and production.

In many cases, men who may be concerned about heat exposure and the impact on sperm health, partaking of at-home sperm tests can provide some detailed information about current sperm quality levels and may confirm that fertility-enhancing lifestyle changes be put in play.