The new findings, published in the journal Fertility and Sterility, do not bode well for men who spend many hours with their laptops on their laps:
The researchers hooked thermometers to the scrotums of 29 young men who were balancing a laptop on their knees. They found that even with a lap pad under the computer, the men's scrotums overheated quickly.
"Millions and millions of men are using laptops now, especially those in the reproductive age range," said Dr. Yefim Sheynkin, a urologist at the State University of New York at Stony Brook, who led the new study.
"Within 10 or 15 minutes their scrotal temperature is already above what we consider safe, but they don't feel it," he added.
So far, no studies have actually tested how laptops impact men's fertility, said Sheynkin, and there is no bulletproof evidence that it would. But earlier research has shown that warming the scrotum more than one degree Celsius (1.8 degrees Fahrenheit) is enough to damage sperm.
This program aired on November 8, 2010. The audio for this program is not available.