Autism is a complex developmental disability that typically appears during the first three years of life. The result of a neurological disorder that affects the functioning of the brain, autism and its associated behaviors have been estimated to occur in as many as 2 to 6 in 1,000 individuals.
In a new study, researchers have identified a number of birth factors that are associated with an increased risk of autism. Several pregnancy complications were linked to autism.
Dr. Emma J. Glasson, from the University of Western Australia in Crawley, and colleagues report their findings in the Archives of General Psychiatry.
The study involved 465 patients born in Western Australia between 1980 and 1995 and diagnosed with autism or a related disorder by 1999. Comparison groups included 481 siblings of the autistic patients and 1313 subjects randomly selected from the population.
Compared with other subjects, autistic patients were more likely to be first born and to have older parents, the authors note. In addition, mothers of autistic patients were more likely than other mothers to experience a near-abortion episode and to have labor lasting less than 1 hour.
Obstetric complications linked to autism included delivery by c-section and a low Apgar score — a standard test to see how the baby is doing immediately after delivery.
“It is unlikely that single factors or events cause (autism), although it is possible that early non-genetic influences” may play a role in some cases, the investigators state. The current findings support the theory that the development of autism primarily depends on genetic factors, they add.