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Hot tubs hurt fertility, UCSF study shows [/size]
Exposure to hot baths or hot tubs can lead to male infertility,
but the
effects can sometimes be reversible, according to a new study led
by a University of California, San Francisco urologist.
Results from a three-year study analyzing data from infertile men who
had been repeatedly exposed to high water temperatures through hot
tubs, Jacuzzis or hot baths are reported in the January-February 2007
issue of “International Braz J Urol,” the official journal of the Brazilian
Society of Urology.
Study findings will be available online at
http://www.brazjurol.com.br.
“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,” said Paul
J. Turek, MD, lead investigator who is a professor in the UCSF Department of
Urology and director of the UCSF Male Reproductive Health Center. “We now
have actual evidence to show patients that these recreational activities are a
real risk factor for male infertility.”
Although this was only a pilot study, Turek said, “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, according to Turek. This is the first published study
to show that total body exposure to wet heat can also impair both sperm
production and motility. Study findings also showed that the negative effect
of this exposure was reversible in nearly half of the infertile men who discontinued
the practice.
An estimated 7 percent of American couples report that they are unable
to conceive a child naturally within one year, according to the 2002 National
Survey of Family Growth, the latest data available to the Centers for Disease
Control and Prevention.
Of those, 30 percent are attributed to the male partner, 30 percent to the female
and the remainder to either both partners or to unknown causes, according to the American Society for Reproductive Medicine.
The ASRM estimates that 85 percent to 90 percent of infertility cases can be effectively treated with drug therapy or surgical procedures. Less than 3
percent require advanced reproductive technologies, such as in vitro
fertilization, but those techniques can be costly. The ASRM cites an average
IVF cost of $12,400 per cycle in the United States.
“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. “Couples
really prefer having kids at home and not with technology. This is a way to help
them do that.”
Turek advises men who would like to conceive a child to “treat your body like
a temple: Eat well, sleep well and take good care of yourself.”
The study’s 11 patients were identified on the basis of repeated exposure to wet
heat and were asked to cease that exposure for three or more months. Five of the patients (45 percent) responded favorably to the cessation of heat exposure and
had a mean increase in total motile sperm counts of 491 percent after three to six months. This increase was largely driven by a statistically significant increase in sperm motility among responders, from a mean of 12 percent at the start of the
study to 34 percent post-intervention.
Of the six patients who did not see an increase in sperm count or motility,
tobacco use emerged as a possible differentiating factor. Five of those patients
were chronic tobacco users with a significant smoking history, in contrast to only
three occasional smokers in the responder group. No other potential gonadotoxic factors – harmful to the male gonad – were identified.
For the purposes of this study, wet heat exposure was defined as the immersion
of the body in a
hot tub, heated Jacuzzi or bath at a temperature warmer
than body temperature for 30 minutes or more per week for at least three months prior to participation in the study. Patients were excluded from the study if they
had received infertility treatments in the previous year, or if female infertility was
a co-existing factor.
The only previously published study to examine this link was performed in 1965, according to the research paper. In that study, 20 men were exposed to direct
scrotal wet heat for 30 minutes on six alternating days. The findings showed a temporary decline in sperm production during the treatments, but there were no details of semen quality before and after the study. An unpublished Swiss study
in the 1940s had also linked wet heat to temporary male infertility.
Concern about wet heat effects on infertility crosses many cultures, Turek
said, citing a centuries-old practice in Japan of
barring childless men from conducting business deals in hot tubs, due to its believed effect on fertility.
Work on this research was begun by UCSF medical student Phiroz E. Tarapore,
who is graduating this spring. Co-authors of the study are Shai Shefi, MD,
Department of Urology, Chaim Sheba Medical Center, Tel-Hashomer, Israel;
Thomas J. Walsh, MD, UCSF Department of Urology; and Mary Croughan,
Phd.
