Link confirmed between autism and mother’s age

February 11, 2010 by Shawn Douglas
Filed under: News

A link has been confirmed between a mother’s age and her risk of giving birth to an autistic child.

New research out of the University of California, Davis shows that older mothers have a higher risk of giving birth to an autistic child, but older fathers only increase the autism risk when the mother is under the age of 30.

“The older the mother, the more the risk that the child will develop autism, regardless of whether the father is young or old,” said Dr. Irva Hertz-Picciotto during a phone interview with Reuters.

The research, published in the February issue of the journal Autism Research, looked at the nearly five million births that occurred in California between 1990 and 1999. From that sample, there were 12,159 children born with autism.

Researchers found that for every five-year increment in age, a woman was 18 percent more likely to have a child born with autism. Thus women 40 to 44 years of age had a more than 50 percent increased risk in birthing an autistic child compared to women between the ages of 25 to 29.

They also found that the father’s age made a significant difference, but only when the mother was considerably younger. Men over 40 who conceived children with a woman under 30 were at a 60 percent increased risk of having an autistic child compared to men between 25 and 29 who conceived a child with a young woman. However, this risk was negated when both the mother and father were older.

“There has been a debate over whether it is maternal or paternal risk. A lot of people were thinking it’s not really mom’s age,” said Hertz-Picciotto.

Yet with the large sample size used in the study, it was easier to clarify the ages of those involved. “We have such a very large database we were really able to disentangle the mother’s age very well,” added Hertz-Picciotto.

Rates of autism — a developmental disorder that causes problems with social and communication skills — increased by 600 percent in the state of California during the 1990s, prompting many to focus more attention on autism research.

“We need to look at this finding in context,” said Geraldine Dawson, chief science officer for Autism Speaks, in an interview with U.S. News and World Report. “This study is important, but we are not going to find one factor that can explain this dramatic increase in the prevalence of autism. We are going to find multiple factors, and advanced maternal age appears to be one of them.”

Reuters reports that the National Institute of Mental Health in the U.S. is focusing its attention on the genetic features of autism. The institute plans to sequence the entire genome of hundreds of autistic children and their parents to find relevant links in genetics that may cause the disease.