What is the effect of bathing in hot water on man's fertility?

Hot baths may reduce the fertility of men!

Bathing in hot tubs may reduce male fertility, researchers say from the United States.
The three-year studies supported men's advice to avoid overheating their sperm.

The sperm count rose 491% in 5 out of 11 men with fertility problems after they stopped bathing in hot water or using hot tubs for a few months.
Other research has shown that heat from a laptop or tight underwear also reduces male fertility, according to the Journal of the Brazilian Society of Urology.
Researchers from the University of California-San Francisco say the decades-old belief that hot water could harm fertility was based on little research.

The men attending the fertility clinic who were exposed to more than 30 minutes of hot water a week were collected during the shower, jacuzzi or hot tubs. After three to six months of staying away from the hot bath, about half of the participants showed a five-fold improvement in sperm counts. The sperm movement increased from 12% to 34% in the responding men to move away from hot baths. Five out of six men who did not show improvement were chronic smokers, which is why researchers are not responding to the hot bath.
The cold center:

Sperm is known to favor the cold environment of growth, which is why the testicles are located outside the man's body in the scrotum.

"These activities should be added to the list of recommendations and things to avoid for men in their perception of their way of life," said Dr. Paul Torick, lead author of the study at the Center for Reproductive Health at the University of California, San Francisco. "Men can improve their fertility by moving away from hot water, Couples will not need to be vaccinated, and they will be able to choose a safer treatment. "Couples prefer to have children at home, not by techniques, that's how they can do it," he says.

According to Torek, another study examining the relationship between hot water and fertility was conducted in 1965.

After men exposed to hot water for 30 minutes on different days, the researchers found a temporary shortage of sperm production, but did not look for quality before and after the study.
Alan Bassey, a senior lecturer in theology at the University of Sheffield, said it seemed self-evident that hot baths were responsible for reducing the number of sperm, but it was not clear how it affected fertility.

Ideally, this study should be repeated with a larger number of patients with more specific control groups before we are certain about the direct risk of hot tubs to reduce male fertility.
Change in sperm quality is important, but what really matters is: (pregnancy). However, men who are interested in their fertility will not be able to take a shower (a quick bath) instead of immersing themselves in the hot tub.