Dads’ ages affect birth defects

With every birthday, men who plan to be fathers put their unborn child at a higher risk of serious psychiatric and developmental disorders.

In a new study, IU researchers discovered babies born to older fathers are more prone to psychiatric and academic problems than previously thought.

“We were predicting very serious problems like autism, ADHD, suicide and schizophrenia with these better research designs,” said Brian D’Onofrio, lead author of the study and professor in the Department of Psychological and Brain Sciences at IU. “The findings were much higher than we expected.” 

The sample set of data was large, coming from every one of the 2.6 million people born in Sweden from 1973 until 2001.

That’s the largest to date for this area of study, D’Onofrio said.
 
From this sample, researchers saw that when a child born to a 24-year-old father was compared to a child born to a 45-year-old father, the latter turned out 3.5 times more likely to have autism, 13 times more likely to have ADHD, two times more likely to have a psychotic disorder, 25 times more likely to have bipolar disorder and 2.5 times more likely to have suicidal behavior or a substance abuse problem.

Scandinavian countries such as Sweden don’t have as many policies regarding privacy when it comes to health records as the U.S., the Department Chair of Psychological and Brain Sciences, Bill Hetrick, said.

This enabled so many people to be included in the sample, which never would have been allowed with U.S. health privacy policy, Hetrick said.

“It demonstrates what can be done with linked electronic medical and health records with educational documents,” Hetrick said. “Scandinavian records prove important to answer these questions. The methodology they use to make records available to analyze is of tremendous value to society.”

This study is the most comprehensive study to date on the effects of paternal aging on childbearing, according to an IU Newsroom press release.

Unlike any other study regarding paternal aging on childbirth, this is the first one to compare siblings and cousins, D’Onofrio said.

This allowed researchers to focus on the biological concerns more than environmental concerns of childbearing age.

“We know men who have children at a very early age are different than men who have children later on,” D’Onofrio said. “Our ability to compare siblings and cousins whose fathers were different ages gave us a better handle of what are the real concerns of childbearing age.”

Studying cousins also helps examine the effects birth order and sibling influence may have had on the study’s results, D’Onofrio said.

The researchers also controlled factors such as parent income and education to see if household stability had any effects.

But the results were the same despite income and education levels.

D’Onofrio said he believes the high rates of psychiatric problems in children born to older parents occur because when sperm replicate, there is a chance for a DNA mutation. Also, as men age, they are exposed to more environmental toxins, which can cause mutations in sperm, he said.

“There are more genetic mutations in sperm of older men,” D’Onofrio said.

When it comes to the effects of parental age on childbirth, paternal aging is a new hot topic for researchers D’Onofrio said.

He said he equates this to trends of waiting to have children.

“Historically there has been an increase in the average age of men and women having children,” D’Onofrio said.

“In fact, in most recent recession, more people waited to have children.”

Research like this shines light on the negative consequences of waiting to have children, and D’Onofrio said he hopes it helps people make more informed choices.

“This research should help inform couples and society at large to consider both the pros and cons of delaying childbearing,” he said.

D’Onofrio said he admits the study needs to be replicated and needs more advanced research designs to better estimate paternal age factors in child bearing.

More genetic research and research on possible environmental associations need to be looked into as well, D’Onofrio said.

D’Onofrio said he finds many people interested in the issue because the wide scope of people it affects.

“Mental health problems affect all of us,” D’Onofrio said. “Whether ourselves, our family, or close friends it’s an important topic for the general public to know about.”

Finally, though paternal aging does pose risks for children developing psychiatric problems, D’Onofrio said he doesn’t want people thinking this happens every time men of older age have children.

“It’s an important public health questions, but I must stress not all children born to older men have psychiatric problems,” D’Onofrio said.