Older fathers are far more likely to have autistic children, experts have warned. Children born to fathers aged 40 and over are around six times more likely to suffer from autism compared to those born to fathers under 30, they said.
But the researchers, including a team from the Institute of Psychiatry at King's College London, could find no link between a mother's advancing age and autism.
Previous studies on a correlation between mother's age and autism have produced mixed results.
The researchers said the findings provided further evidence that men also have a "biological clock" when it comes to producing healthy babies.
Dr Abraham Reichenberg, from the the Mount Sinai School of Medicine in New York, and the Institute of Psychiatry worked with other researchers to assess Jewish children born during the 1980s in Israel.
They looked at information for 132,271 children for the study, published in the Archives of General Psychiatry.
They found that if the father was aged 15 to 29 when their child was born, the risk of autism was six in every 10,000 children.
If the father was aged 30 to 39, then nine in 10,000 children suffered autism (1.6 times higher), going up to 32 in 10,000 (5.75 times higher) for fathers aged 40 to 49. The risk was even higher among fathers aged 50 and over, although the sample size was small.
Dr Reichenberg said: "This research adds to our knowledge that men also have a biological clock when it comes to reproducing.
"The sample size for the over-50s was small so we added it to the results for fathers aged over 40, but our research suggests that very old fathers have around nine times the risk. The research shows a linear effect - with every 10 years, the risk doubles."
