Low birth-weight babies were found to be five times more likely to have an autism spectrum disorder later in life than average-weight babies in a new study published in the journal Pediatrics.
Researchers followed 1,105 children born weighing less than 4.5 lbs between 1984 and 1987. When the children were screened for autism at age 16, researchers found 117 of the 623 children screened positive.
"It was very high, and we thought we had a great opportunity to really evaluate them for autism with a diagnostic test," Jennifer Pinto-Martin, director of the Center for Autism and Developmental Disabilities Research and Epidemiology at the University of Pennsylvania and the study's lead author, told Time.
Researchers were able to evaluate 70 of the 117 children who had screened positive and 119 of the 506 children who had screened negative when they reached age 21. They found 14 cases of autism spectrum disorder, a rate of incidence five times higher than that reported in the general population.
"[Centers for Disease Control and Prevention]data says it's about one per cent in eight-year-olds, and we found it to be five per cent in 21-year-olds," Pinto-Martin said.
She added that screening children for ASD should become a routine part of pediatric care.
"The same way we make sure every kid gets screened for hearing, we need to make sure that every kid gets screened for autism spectrum disorders."
While low birth-weight has been linked to a range of developmental disorders in previous studies, researchers said this was the first to draw a connection to autism spectrum disorders.
Dorothy Bishop, professor of developmental neuropsychology at the University of Oxford, told the BBC that the study shouldn't send parents of preemies in to a panic.
"The association looks real, but nevertheless, most low birth-weight children don't have autism, and most children with autism don't have low birth-weight," she said.