Child health linked to father’s age

A wide range of disorders and problems in school-age children have been linked to delayed fatherhood in a major study involving millions of people, BBC News reported.

Increased rates of autism, attention deficit hyperactivity disorder (ADHD), bipolar disorder, schizophrenia, suicide attempts and substance abuse problems were all reported.

The study, in JAMA Psychiatry, suggests mutated sperm were to blame.

However, experts say the benefits older dads bring may outweigh any problems.

The investigation by Indiana University, in the US, and Sweden's Karolinska Institute has been described as the largest and one of the best designed studies on the issue.

The researchers looked at 2.6 million people and at the difference between siblings born to the same father as it accounts for differences in upbringing between families.

There was no starting point after which the risk started to increase, rather any increase in age had an associated increase in risk.

However, the overall risk is likely to remain low. Even if the risk of a rare disorder is doubled, it is still very unlikely to affect a child.

The problem is small increases in risk scaled up over millions of people having children later can lead to an increased incidence of such disorders.

One of the researchers, Dr Brian D'Onofrio, said he was shocked by the findings, which suggested a higher risk than previously estimated.

He told the BBC: "The implications of the study is that delaying childbearing is also associated with increased risk for psychiatric and academic problems in the offspring.

"The study adds to a growing body of research, that suggests families, doctors, and society as a whole must consider both the pros and cons of delaying childbearing."