Lead author Jennifer Pinto-Martin of the University of Pennsylvania School of Nursing in Philadelphia and colleagues tracked 862 children for 21 years and found premature infants with low birth weights were five times more likely to have autism spectrum disorders than children born at normal weight.
The infants were born from September 1984 through July 1987 at birth weights as low as 1 pound to a maximum of about 4.4 pounds, Pinto-Martin said.
Pinto-Martin and colleagues at The Children's Hospital of Philadelphia, described the research as "the first study to have estimated the prevalence of autism spectrum disorders ... using research validated diagnostic instruments."
"As survival of the smallest and most immature babies improves, impaired survivors represent an increasing public health challenge," Pinto-Martin, director of the Center for Autism and Developmental Disabilities Research and Epidemiology at the university, said in a statement.
"Emerging studies suggest that low birth weight may be a risk factor for autism spectrum disorders."
The findings are published in the journal Pediatrics.