Babies born with low birth weight have a considerably greater chance of being diagnosed with an autism spectrum disorder, compared to those born with normal weight, researchers from the University of Pennsylvania's School of Nursing and School of Medicine wrote in the journal Pediatrics. The authors considered a baby born weighing less than 2 kg (4.4 lbs) to be of low birth weight.
As background information, the authors explained that previous studies had found an association between low birth weight, prematurity and a higher risk of motor and cognitive disability. However, prior studies' links with ASD (autism spectrum disorders) were not compelling - they were retrospective studies and subjects were screened without diagnostic confirmation.
Jennifer A. Pinto-Martin, PhD, MPH and team carried out a longitudinal study of a cohort of 1,105 children who were born at low birth weight. They were born at three central New Jersey counties. The children were born between October 1984 and July 1989.
They screened 623 of them and checked their medical records for details of ASD when they were 16 years old.
They then carried out rigorous diagnostic assessments on 117 of the ones who had screened positive for ASD and 119 of the 506 who had screened negative.
11 of the 70 who were screened positive for ASD were diagnosed with ASD as young adults, while among those with negative screens, 3 of 199 were diagnosed with ASD.
After factoring out various variables, the authors calculated that the babies born with low birth rate had a 5% risk of eventually being diagnosed with ASD, compared to the 1% overall estimate of all children by the CDC (Centers for Disease Control and Prevention) - a five times higher risk for the low weight newborns.
In an Abstract in the journal, the authors wrote:
"The diagnostic prevalence of ASD in this LBW preterm cohort was higher than that reported by the Centers for Disease Control and Prevention for 8-year-olds in the general US population in 2006."
According to the NIH (National Institutes of Health), approximately 3% of US babies are born weighing between 1.1 and 4.4 pounds (500g and 2 kg).
Pinto Martin said:
"Cognitive problems in these children may mask underlying autism. If there is suspicion of autism or a positive screening test for ASD, parents should seek an evaluation for an ASD. Early intervention improves long-term outcome and can help these children both at school and at home.
"The number of children with a diagnosis of autism is on the rise and we haven't been able to explain why. It's partly a function of awareness and better diagnosis, but we do a better job of keeping tiny babies alive and this may be one consequence of that. "Written by Christian Nordqvist
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