Men who carry their mobile phone in a trouser pocket or talk on it for just an hour a day risk suffering from infertility thanks to a low sperm count, scientists warn.
Research shows that a man's sperm count can even be reduced by talking on a phone that is charging, or even keeping it close by on a bedside table at night.
Heat and electromagnetic activity which emanate from a mobile phone are thought to "cook" sperm, causing them to die.
For the study, Israeli scientists monitored 106 men attending a fertility clinic for a year.
The results showed that those who chatted on the phone for more than an hour daily were twice as likely to have low sperm quality as those who spoke for less than an hour.
Men who used the phone as it charged were almost twice as likely to suffer problems, the results revealed.