Men should keep their laptops off their laps because they could damage fertility, according to a new medical study released today. Researchers said that laptops can heat up the scrotum which could affect the quality and quantity of sperm. “The increase in scrotal temperature is significant enough to cause changes in sperm parameters,” said Dr. Yefim Sheynkin, an associate professor of urology at the State University of New York at Stony Brook. “It is very difficult to predict how long the computer can be used safely. It may not be at all, if the testicular temperature goes up high within a very short period of time.”