They decrease sperm number and motilityAbout 7 % of American couples are sterile. 30 % of the cases are attributed to the man, 30 % to the woman and the rest to both partners or to unknown reasons. Drugs or surgery can treat 85-90 % of infertility cases; less than 3 % require in vitro fertilization (IVF), a costly procedure. "Couples really prefer having kids at home and not with technology", said professor Dr. Paul J. Turek, lead investigator who is director of the Department of Urology and Male Reproductive Health Center at the University of California, San Francisco.
His team found that exposure to hot baths or hot tubs can inflict infertility in men, but these effects can be reversible in some cases. "It has been believed for decades that wet heat exposure is bad for fertility, as an old wives' tale, but this effect has rarely been documented. We now have actual evidence to show patients that these recreational activities are a real risk factor for male infertility."
"These activities can be comfortably added to that list of lifestyle recommendations and 'things to avoid' as men attempt to conceive. Dry heat exposure, for instance, as presented with fevers or through applied external heat, is a well-documented cause of impaired sperm production in both animals and humans", said Turek.
This three-year research is the first to report impaired fertility (both for sperm production and motility) in men who had been repeatedly exposed to wet heat. Wet heat exposure was defined as the immersion of the body in a hot tub, heated Jacuzzi or bath at a temperature higher than 37o C (normal body temperature) for 30 minutes or more weekly for at least three months before entering in the research pool. "One implication of this work is that a simple lifestyle maneuver could 'shift the care' from high-tech intervention to low-tech or no-tech," Turek said.
The 11 subjects were asked to stop that exposure for three or more months. Five (45 %) experienced a total motile sperm increase of 491 % after three to six months and total results (for the 11 subjects) revealed an increase from 12 % at the beginning of the investigation to 34 % post-intervention.
In the six patients that did not respond to the approach, the culpable factor was found to be chronic tobacco smoking (in five of them). Other potential toxic factors for the testes were not found and patients did not take infertility drugs, nor was the female partner the cause of the couple's sterility. "Concern about wet heat effects on infertility crosses many cultures", said Turek. An old Japanese habit forbids childless men to make business deals in hot tubs, as it is regarded as a sterility inducing factor!