Testis cross section

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While the female system has long taken the brunt of the blame for fertility problems, male reproductive factors actually make up 50% of all cases of infertility. But let’s hand it to them, the testes do an astonishing amount of work: they manufacture sperm at a rate of 1,000 sperm cells per heart beat, which tallies up to hundreds of millions of sperm per day. In part because the testes are so active, they are also extraordinarily sensitive to outside factors like chemicals, heat, alcohol, and stress.

Dr. Marc Goldstein, Director of the Center for Male Reproductive Medicine and Microsurgery at the New York Presbyterian Hospital Weill Cornell Medical Center and co-author of A Baby at Last!, comments on the most common – and peculiar – factors that affect male fertility.

Keep the Laptop on the Table.

Heat is a major enemy of the testes, which is precisely why they hang outside of the body. Doing so keeps them 2-4° C cooler than the body temperature. When testicle temperature rises, sperm production is significantly slowed. Goldstein tells his patients to avoid placing laptop computers on their laps (there has actually been research on this), and even to avoid using saunas and hot tubs on a regular basis. He also tells men not to “sit at a desk with your legs crossed for long periods. Stand up and shake everything out once in a while.”

Briefs Are Fine.

The well-loved myth that briefs inhibit fertility has actually been invalidated in a randomized prospective study that showed that there was no difference in testis temperature in men who wore briefs vs. boxers. That being said, Goldstein advises men not to don “plastic pants or Mick Jagger pants,” which could raise the temperature enough to have a negative effect on sperm production. (Biking does not seem to have a negative effect on fertility, but avoiding spandex biking shorts is recommended.)