Washington, April 28 (Inditop) Children who are first born or emerge with their feet first in breech birth or whose mothers are 35 or older, face greater risk of developing autism.

University of Utah School of Medicine researchers showed that women who give birth at 35 or older are 1.7 times more likely to have a child with an autism spectrum disorder (ASD), as compared to women between the ages of 20-34.

Autism is a complex brain disorder that impairs social, communicative, and behavioural development and is often characterized by extreme behaviour.

Children diagnosed with ASD also were nearly 1.8 times more likely to be the first born child, the researchers found.

Although they didn’t identify a causal relationship between breech births and autism, children diagnosed with the disorder were more than twice as likely to have been a breech presentation, meaning they were not born head first.

“The results of this study give us an opportunity to look more closely at these risk factors for children across the autism spectrum,” said study co-author Deborah A. Bilder, assistant professor of psychiatry, Utah University.

Bilder and colleagues examined the birth records of Utah children who had been identified as having autism spectrum disorder in a 2002 epidemiological study by the US Centre for Disease Control and Prevention (CDC), said a Utah release.

These findings were published in the Monday online issue of Paediatrics.