Men who rest computers on their laps for long periods could be risking their fertility, Italian scientists warned Tuesday.

Researchers in the northern city of Padua said laptops could cause overheating in the genitals, damaging the user's ability to produce sperm, the ANSA news agency reported.

Their study found that when a man rested a device on his groin the temperature of his testicles rose by two degrees Celsius (about four degrees Fahrenheit) in one hour.

Andrologist Carlo Foresta of Padua University said that a one degree Celsius increase was enough to impair the production of sperm. Wearing tight pants, taking a sauna or having a fever can apparently have the same effect.

"It's quite usual to see young men holding their laptops on their laps, especially on trains, and we've found that this habit can raise the temperature of the testicles by two degrees in an hour," he said.

"Infertility is associated with a rise in temperature, which in both groups was about one degree."
Full details of the study will be unveiled in Rome later this month, ANSA said.