LONDON: Teenagers and young men should keep their laptops off their laps because they could damage fertility, an expert says.

Laptops, which reach high internal operating temperatures, can heat up the scrotum which could affect the quality and quantity of men’s 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, on Thursday.

“It is very difficult to predict how long the computer can be used safely,” he told Reuters. “It may not be at all, if the testicular temperature goes up high within a very short period of time.”

Adolescents and young men who use laptops several times a day over many years face the greatest risk. Sheynkin fears that if laptop use is not curtailed, in 15-20 years when they want to start a family the men could face problems.

“Long-term use may have a detrimental effect on their reproductive health,” he said.

Sheynkin and his team studied the impact of using a laptop on 29 healthy volunteers between the age of 21-35 by measuring scrotal temperature before and after they used a computer on their lap.

The research is reported in the journal Human Reproduction.