Older Parents, Birth Order Linked to Autism

Older Parents, Birth Order Linked to Autism
By John M. Grohol, Psy.D.
January 4, 2009
In the largest study ever to look at correlations related to autism, researchers at the University of Wisconsin-Madison discovered that birth order and a parent’s age are important factors.

Specifically, the researchers found that the risk of a firstborn child having an autism-related disorder triples after a mother turns 35 and a father turns 40.

The researchers also found a 20 percent increase in the risk of autism with each 10-year increase in the parents’ ages. They also found a couple’s fourth child has half the risk of the first, regardless of the parents’ ages.

The researchers don’t yet have much in the way of pinpointing specific causes that might explain these findings:

“Is this pure genetics? Or a toxic phenomenon?” said Darold Treffert, former president of the Wisconsin Medical Society, a psychiatrist at St. Agnes Hospital in Fond du Lac and an expert in savant syndrome. Treffert was not involved in the study.

“I think we’re bombarded with all sorts of stuff. And we know from experiences such as thalidomide that there are specific times during development of specific risks with specific chemicals. The problem is there is just so much out there.”

Like many things in this realm, the answer is likely a complex combination of factors relating both to genetics and environment. The firstborn statistic, while intriguing, is an anomaly likely explained by the fact that many parents who give birth to an autistic child simply stop having any additional children, as the researchers note.

One take-away from this study is that you put your future firstborn child at risk if you wait to have children until you’re older, as many people in society are doing (focusing first on their own careers or what-not). This study clearly shows a relationship between higher autism spectrum disorders’ risk and waiting to have children.

Read the full article: UW researcher finds link between age, birth order and autism