News The latest developments in autism research.
Profiles Portraits of scientists who are making a mark on autism research.
Toolbox Emerging tools and techniques that may advance autism research.
Spotted A roundup of autism papers and media mentions you may have missed.
Opinion Conversations on the science of autism research.
Viewpoint Expert opinions on trends and controversies in autism research.
Columnists Dispatches from experts on various facets of autism.
Crosstalk Debates and conversations about timely topics in autism.
Reviews Exploring the intersection of autism and the arts.
Q&A Conversations with experts about noteworthy topics in autism.
Deep Dive In-depth analysis of important topics in autism.
Special Reports Curated collections of articles on special topics in autism.
Webinars Presentations by leading experts on their latest research.
Opinion

Age of parents explains little of surge in autism

by  /  31 March 2015

William Perugini/Shutterstock.com

The growing prevalence of autism over the past two decades has coincided with an uptick in parental age in the U.S. Some studies suggest that children born to older mothers and fathers have an increased risk of the disorder. This raises the question: Is advanced parental age fueling autism’s rise?

Probably not, suggests a study published 17 March in Maternal and Child Health Journal. The report finds that increased parental age accounts for just 2.7 percent of the rise in autism prevalence between 1994 and 2001.

Researchers analyzed birth information for 927,003 children born in New York City between 1994 and 2001, including 1,640 with autism. The information came from the Longitudinal Study of Early Development, which collects health and education information on children born to women who live in the city.

Within the study period, the proportion of children with a mother or father aged 35 or older rose by roughly 15 and 10 percent, respectively. The prevalence of autism also increased from 1 in 3,300 children to 1 in 233.

The researchers looked at how the risk changes with age, dividing mothers and fathers into four groups: younger than 25, aged 25-29, aged 30-34, and 35 or older. Compared with mothers under the age of 25, those between the ages of 25 and 29 were 1.5 times more likely to have a child with autism. The risk was 1.6 times higher for women aged 30-34, and 1.9 times higher for those aged 35 or older.

Men aged 35 or older were 1.4 times more likely to have a child with autism than those under the age of 25 — a finding that jibes with that of a 2012 study of 1.3 million Danish children.

Still, the increase in parental age over time accounts for a small fraction of the surge in autism prevalence. The bulk of the rise most likely stems from increased awareness of autism and changes to how doctors diagnose the disorder, the researchers say.

It’s still unclear why autism risk increases with parental age. It could be that sperm from older fathers are more susceptible to spontaneous mutations than those from younger dads. Or perhaps it’s because older would-be mothers are more prone to pregnancy complications, such as premature birth or gestational diabetes, that themselves raise autism risk. Whatever the reason, older parents can rest assured that their risk of having a child with autism is still quite small.


  • Lynn Schnebly

    Given the research done in the area of maternal and paternal age and the incidence of autism, 35 is not a good break point. The difference in autistic rates goes up several times as one moves beyond 40, especially in men. Men age 40-45 will have a higher incidence, 45-50 higher still, 50-55 – about 5.5 times the incidence of a 25 year old man. Also, given that 35 is not the break point listed in international studies for an increase in incidence, and the vast majority of the children born after the age of 34 are with fathers 35-42, not within the questionable age grouping, one must question the inclusion of this group in the study. I wonder what the numbers look like when this large “normal age” population is added to the younger aged fathers and the real break point is about 42 (looking at 5 year increments from that point on). There are also studies that see significant increases in autism, and other disorders and birth deformations in parents with significant age differences.

close

Log in to your Spectrum Wiki account

Email Address:

Password:


close

Request your Spectrum Wiki account

Spectrum Wiki is a community of researchers affiliated with an academic or research institutions. To be considered for participation, please fill out this form and a member of our team will respond to your request.

Name:

Email Address:

Title and Lab:

Area of Expertise:

Comments: