Researchers* warned that men should not rest lap top computers on their laps, or even sit for a more than a few minutes with their thighs together, if they are trying for a child. In just fifteen minutes a laptop's processor can raise the temperature of the scrotum by 1°C, sufficient to reduce the live sperm count by 40% and damage the surviving sperm. Sixty minutes' use can raise the scrotum's temperature by nearly 3°C, wiping out all current sperm.

When men simply sat with their thighs together for sixty minutes, the temperature of their scrotum rose by 2°C.

* Yefim Sheynkin and colleagues at the University of New York at Stony Brook (US)