For years, men have been told to stay out of the hot tub if they're trying to get pregnant. Now, a researcher at the University of California, San Francisco has started to document the reality of the common sense tale.
The bad news: hanging out in "wet heat" situations -- hot tubs and long baths for 30 minutes or more a week for at least 3 months -- really can impair sperm production and motility.
The good news: the effects on sperm of wet heat appear to be reversible without treatment.
A pilot study with 11 subjects, all of whom were regularly immersing their bodies in hot water, showed a mean increase in total motile (moving) sperm count of 491 percent after three to six months of refraining from dunking.
The researchers believe that six of the subjects who saw no increase in sperm count or motility were probably left out of the benefits of no-hot-tubbing because they were heavy cigarette smokers, a known factor in sperm production and quality.
The study was published in the January-February issue of International Brazilian Journal of Urology. You can also read a quick summary of the findings in the PR from UCSF.