For the first time, researchers have announced that an ultrasound test conducted after birth can determine a child's risk for developing autism.

A study led by Michigan State University found that newborns with low birth weight are seven times more likely to develop autism later in life if ultrasound scans taken immediately after birth shows enlarged ventricles, brain cavities that store spinal fluid.

Enlarged ventricles are more common in premature babies, and may indicate loss of white matter, the connective tissue in the brain.

The study, supported by a grant from the National Institutes of Health, was published in the Journal of Pediatrics and may indicate a method for early detection of autism that could go into widespread use.

Autism spectrum disorder is still poorly understood, and there has been much controversy in recent years over whether environmental causes might influence the development of the disorder, which can be diagnosed by behavioral tests as early as age two or three but typically becomes more pronounced later on.

"There's always the question of at what age a child begins to develop the disorder," said lead author Dr. Tammy Movsas, clinical assistant professor of pediatrics at MSU and medical director of the Midland County Department of Public Health.

"What this study shows us is that an ultrasound scan within the first few days of life may already be able to detect brain abnormalities that indicate a higher risk of developing autism."

Movsas and colleagues analyzed data from a cohort of 1,105 low-birth-weight infants born in the mid-1980s in order to come to this conclusion.

The babies had cranial ultrasounds immediately after birth, so researchers could look for relationships between brain abnormalities in infancy and health disorders that developed later.

Participants were screened for autism at age 16, and a subset of them had a more rigorous test at 21, which turned up 14 positive diagnoses.

"This study suggests further research is needed to better understand what it is about loss of white matter that interferes with the neurological processes that determine autism," said co-author Nigel Paneth, an MSU epidemiologist who helped organize the cohort that was studied. "This is an important clue to the underlying brain issues in autism."