Leaving fatherhood later in life could put your children at increased risk of a huge range of psychological and educational problems, US scientists have warned.
In a massive study of more than 2 million children, the scientists have found that, compared to children of a 24-year-old father, children of 45-year-old father are 3.5 times more likely to suffer from autism, 13 times more likely to have ADHD, 25 times more like to have bipolar disorder and more likely in general to have lower IQ scores and poorer academic performance.
“We were shocked by the findings,” says Brian D’Onofrio, study author and associate professor in the Department of Psychological and Brain Sciences at Indiana University. “The specific associations with paternal age were much, much larger than in previous studies. Our findings suggest families, doctors, and society as a whole must consider both the pros and cons of delaying childbearing.”
The scientists think the reason for their finding lies in sperm quality. Men continue to make new sperm all their lives (unlike women who are born with a finite number of eggs) but, as men age, their sperm-making mechanisms start to throw more and more errors, causing increasing mutations in the sperm’s DNA. And it’s these gene mutations that have the potential to cause health problems in older men’s children.
The study findings are particularly relevant as UK statistics show both men and women are leaving it later to have children. According to figures from the Office for National Statistics, the average woman gives birth at 30, and the average age of fathers is now 32 years and six months.
Commenting on the new study, Dr Allan Pacey, fertility expert at the University of Sheffield, said men should be thinking about having children as young as possible.
“This is the biggest and most comprehensive study of its kind,” he says, “and it really highlights that there is a time limit for dads on when they should have their children. I think the changes start to take place when a man gets to 40.
“My advice would be that if you are in a position to have your family early then do it, even if you want to wait a bit longer. Nature wants you to have children early.”