Using a laptop wirelessly connected to the internet can harm a man’s fertility, researchers have warned.

Concern: A quarter of sperm exposed to WiFi radiation in the study were no longer swimming around after four hours

They discovered that WiFi radiation can ‘nuke’ sperm – meaning the risk arises when the machine is used as it was designed and placed on the lap.

When the wireless connection is switched on it creates electromagnetic radiation that damages semen, the scientists said.

The Argentinian researchers made the connection after taking semen samples from 29 healthy men, placing a few drops under a laptop hooked into the internet via WiFi and hitting download.

Four hours later some of the sperm appeared to have been nuked by WiFi radiation.

It may be convenient, but using a laptop on your lap could be harming your sperm, say researchers (file picture)

A quarter of the sperm were no longer swimming around, compared with just 14 per cent from semen samples stored at the same temperature away from the computer.

And 9 per cent of the sperm showed DNA damage, three-fold more than the comparison samples.

Lead researcher Conrado Avendano of Nascentis Medicina Reproductiva in Cordoba says the culprit is electromagnetic radiation generated during wireless communication.

Writing in the venerable medical journal Fertility And Sterility, he says: ‘Our data suggest that the use of a laptop computer wirelessly connected to the internet and positioned near the male reproductive organs may decrease human sperm quality.

‘At present we do not know whether this effect is induced by all laptop computers connected by WiFi to the internet or what use conditions heighten this effect.’

A separate test with a laptop that was on, but not wirelessly connected, found negligible EM radiation from the machine alone.

Concern: A quarter of sperm exposed to WiFi radiation in the study were no longer swimming around after four hours

The findings fuel concerns raised by a few other research teams.

Some have found that radiation from mobile phones creates feeble sperm in the lab, for example.

And last year urologists described how a man sitting with a laptop balanced on his knees can crank up the temperature of his scrotum to levels that aren’t good for sperm.

So between the heat and the radiation from today’s electronic devices, testicles would seem to be hard-pressed.

However, Dr Robert Oates, the president of the Society for Male Reproduction and Urology, has managed to father two kids despite having both a laptop and an iPad.

He told Reuters Health he doesn’t believe laptops are a significant threat to male reproductive health.

Remarking on the new study, he said: ‘This is not real-life biology, this is a completely artificial setting.

‘It is scientifically interesting, but to me it doesn’t have any human biological relevance.’

He added that so far, no study has ever looked at whether laptop use has any influence on fertility or pregnancy outcomes.

‘Suddenly all of this angst is created for real-life actual persons that doesn’t have to be,’ said Oates, also of Boston Medical Center.

He added: ‘I don’t know how many people use laptops on their laps anyway.’

According to the American Urological Association, nearly one in six couples in the U.S. have trouble conceiving a baby, and about half the time the man is at the root of the problem.

While the impact of modern technology is still murky, lifestyle does matter, researchers say.

Earlier this month, a report in Fertility And Sterility showed that men who eat a diet rich in fruit and grains and low in red meat, alcohol and coffee have a better shot at getting their partner pregnant during fertility treatment.