June 8, 2004 -- Autism is linked to problems at birth, new data show.
Now scientists trying to trace the roots of autism have a new clue. Kids who later develop autism tend to have more birth complications than normal kids do. The findings come from Emma J. Glasson, PhD, University of Western Australia, and colleagues.
"We found an association between adverse obstetric experience and the development of autism later in life," Glasson tells WebMD in an email interview.
The data come from 465 children with autism, 481 of their normal brothers and sisters, and 1,313 normal kids without autistic siblings. Information on the children was collected at time of birth and matched to later data from a registry of children with autism.
The findings appear in the June issue of the Archives of General Psychiatry.
No Single Birth Factor Linked to Autism
Not every child with autism has a difficult birth. In fact, some have quite normal births, Glasson says. But as a group, autistic children had more birth problems than normal kids did. These problems included:
As a group, autistic children's mothers gave birth at an older age. And autistic children tended to be firstborns.
None of these problems caused autism, Glasson is quick to point out.
"It is unlikely that the obstetric events found in our study contribute to the development of autism," she says. "It's more likely that a number of children who have some of the supposed genes for autism are experiencing more difficulties because of the combination of genes they have."
Support for this idea comes from an additional finding. The sisters and brothers of autistic children had more birth complications than kids without autistic siblings. But they had fewer problems than their autistic siblings did. This suggests that the normal brothers and sisters inherited some, but not all, of the genes -- and shared some, but not all, of the environmental factors -- that underlie autism.
The findings add weight to previous data suggesting that the roots of autism extend back to a child's earliest days, says Opal Ousley, PhD, a research fellow at Emory University School of Medicine.
"It suggests that the events that produce autism are there before the behavioral manifestations of autism," Ousley tells WebMD. "The problem is that a lot of the findings are mixed. It is possible that autism is caused by many different things -- multiple genes, and multiple interactions between genes and the environment. Autism could be a common outcome of many different causes."
Autism Not Mothers' Fault
This does not in any way mean that mothers are to blame for their children's autism.
"[Parents] should not be worried that they contributed in any way to their child's autistic behaviors," Glasson says. "Plenty of children are born with assisted delivery or have older mothers and have perfectly normal development after birth."
While the study offers new clues, it leaves many questions unanswered. One of them is why, exactly, kids who develop autism have more difficult births than other kids do.
"That's the big question. Unfortunately, the nature of the data we collected does not give us any answers," Glasson says. "Research has a long way to go yet to accurately describe the causes of autism in children. This study has shown that some children who develop autism experience more difficulties [in the womb] and during delivery. The reasons for this are unknown, but may become clearer when information about the causes and associations of autism disorders become known."