Laptops and infertility: It matters how you sit

If guys can find a way to operate laptop computers with their legs apart, they might limit their risk of infertility, a new study finds. Keeping the legs splayed while using a laptop generated substantially less damaging heat in the scrotum than keeping legs together, scientists report online November 8 in Fertility and Sterility. Putting a shield under the laptop didn’t seem to help beat the heat.

A hot scrotum is no laughing matter. The testes generally are 2 to 4 degrees Celsius cooler than standard body temperature, a unique environment conducive to the rapidly dividing nature of sperm cells. Heating the area can trigger oxidative stress, slow the motion of sperm and lessen their ability to fertilize an egg for weeks or months, says Edmund Sabanegh, a urologist at the Cleveland Clinic in Ohio.

In the new study, urologist Yefim Sheynkin of Stony Brook University in New York and his colleagues enlisted 29 men ages 21 to 35 to participate in three tests in which each man operated a laptop computer on his thighs for one hour. One test entailed keeping the thighs together while using the machine. A second required the same position, but with a padded shield placed under the laptop. The third test allowed the men to keep their legs apart at a 70-degree angle as they used a laptop with a shield supporting it that was wide enough to reach across both legs and stabilize the computer.

Each of the men completed all three tests, but did only one test per day. Before each experiment, sensors recorded the scrotum temperature of each volunteer and recorded any changes during the session.

All three uses of a laptop increased the men’s scrotal temperature substantially from pretest levels, but keeping the legs splayed limited this increase to about 1.4 degrees C during the hour-long test. When the legs were kept together the temperature rose by 2.2 degrees with a shield and 2.3 degrees without one.

What’s more, it took an average of 28 minutes for scrotal temperatures to rise 1 degree C when the men had their legs apart, but only 14 minutes to increase that much when they kept their legs together with a shield and 11 minutes with legs together and no shield.

“Having the legs together, which is how most people use laptops, does seem to be the worst,” Sabanegh says. “This makes a lot of sense.”

The laptop shields — also called laptop pads or trays — are sold online and in office-supply stores, though not typically as protective devices, says Sheynkin. He recommends that men put laptops on desks or tables, which enables them to move their legs around and avoid being trapped in a single position for extended periods.

Sabanegh says that many men have come to understand the risks of increasing the scrotum temperature. While such heat may not always be the underlying problem for a couple with fertility issues, it’s part of counseling. “I tell them, ‘Try to be healthy in all the ways you can.’ And that means stop putting laptops on your lap, stop using hot tubs and other things of that nature.”