Does Heat Damage Male Fertility? What Scientific Studies Say

Various scientific studies have begun to link the impact of heat waves with alterations in male reproductive health. 

Researchers in Argentina have found that exposure to high temperatures during sperm formation can reduce both sperm count and morphology .

According to this research, men who experienced heat waves during this process had an average of 58 million motile sperm, around 7 million fewer than those not exposed to extreme temperatures.

Effects of heat on male reproductive health

Although the finding raises concerns about how climate change and extreme temperatures could affect male fertility, experts caution that the relationship between ambient heat and a significant decline in semen quality is not so direct.

Dr. Ramón Lozano Calderón, a specialist at the Faculty of Higher Studies (FES) in Zaragoza, explained that the testicles are anatomically designed to withstand heat. “The scrotum has multiple layers of muscle that function as a natural cooling system. Furthermore, its location outside the body allows it to remain 1.5 to 2°C below body temperature,” he explained.

Experimental tests: How harmful is heat?

To contextualize the potential effects of heat on male fertility, the doctor cited a study published in the Asian Journal of Andrology, in which 20 men underwent controlled sessions of testicular heating. Exposure to 43°C water baths for 10 30-minute sessions reduced sperm count, concentration, and motility, and increased DNA fragmentation.

However, Lozano Calderón emphasized that the duration and intensity of the heat wave in a typical heat wave do not match the extreme conditions of the experiment. “If ambient heat were a determining factor, regions like northern Mexico or the Sahara would see a drop in birth rates, which is not the case,” he noted.

Other factors that affect semen quality

The specialist also emphasized that several factors can influence male fertility, even more than ambient heat. These include:

• Hormonal imbalances, such as low testosterone production.
• Erectile dysfunction can make it difficult to ejaculate effectively.
• Sperm disorders, such as oligospermia (low concentration), asthenospermia (low motility), or teratospermia (abnormal morphology).
• Unhealthy lifestyle, including chronic stress, drug and alcohol use, and obesity.
• Frequent use of tight clothing which raises scrotal temperature and affects sperm production.

Although the human body has effective thermal self-regulation systems, the increasing intensity and frequency of heat waves caused by climate change could put pressure on these mechanisms. Therefore, experts consider it crucial to further research the effects of extreme heat on male reproductive health.