Family Matters

Risk of Autism Is Five Times Higher in Low-Birthweight Babies

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Low-birthweight babies are at risk for all sorts of motor and cognitive delays, and researchers have just added autism to the list. A new study from the University of Pennsylvania finds that premature babies weighing less than 4.5 lbs. at birth are five times more likely than babies born at a normal weight to have an autism spectrum disorder (ASD).

Routine screening for ASD is especially critical in light of medical advances that regularly save babies as little as 1 lb. “It’s a public health red flag,” says Jennifer Pinto-Martin, director of the Center for Autism and Developmental Disabilities Research and Epidemiology at the University of Pennsylvania (Penn) and the study’s lead author. “We have a wave of these children coming down the pike because neonatal care has improved so dramatically. We are saving more and more babies, and the consequences for their health are going to be profound.”

The conclusions, which are published Monday in the journal Pediatrics, are the results of a study that began more than two decades ago. Researchers initially followed 1,105 children who were born in three New Jersey counties between 1984 and 1987, some of whom weighed just a pound at birth.

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Researchers evaluated the children at ages 2, 6, 9, 16 and 21, looking each time at different outcomes — behavioral, academic and psychiatric, to name a few. At age 16, they screened the children for autism. What they found was surprising: 117 of the 623 children screened positive, while 506 screened negative.

“It was very high, and we thought we had a great opportunity to really evaluate them for autism with a diagnostic test,” says Pinto-Martin, who is also a professor in the School of Nursing at Penn.

That’s exactly what Martin did when the preemies turned 21. She was able to catch up with 70 of the 117 who had screened positive and 119 of the 506 who had been negative. It was important to evaluate both groups thoroughly using diagnostic tests because screening tools are not 100% accurate.

They wound up with a total of 14 cases of ASD, which equates to five times the rate of autism reported in the general population. “CDC data says it’s about 1% in 8-year-olds, and we found it to be 5% in 21-year-olds,” says Pinto-Martin.

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Alycia Halladay, director of environmental research for Autism Speaks, said the study was particularly interesting because it focused on older children as opposed to most autism research, which looks at younger kids. “What’s interesting is the 16-year-olds showed a very different profile than other children,” says Halladay. “These kids, on average, tended to have  a higher IQ than a different study that tracked all kids with autism. So maybe low-birthweight children have a different developmental course.”

It’s possible that children born at low birthweights have a variety of additional disabilities — language disorders, for example, or mental retardation — that have may have masked an ASD diagnosis in the years before autism awareness increased. To make sure cases of autism aren’t overlooked, Pinto-Martin advises routine screening for ASD be institutionalized as part of pediatric primary care. At Penn, researchers are working on using trained pediatric nurses in this role.

“There’s so much that needs to fit into a pediatric visit that developmental concerns may not get brought up,” she says. “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.”

Parents, for their part, shouldn’t be overly alarmed, but they should be certain to have their child evaluated as they develop. “Five percent is not 50% but if you a suspicion as a parent, you are probably right. Don’t take wait-and-see as an answer,” says Pinto-Martin.

Bonnie Rochman is a reporter at TIME. Find her on Twitter at @brochman. You can also continue the discussion on TIME‘s Facebook page and on Twitter at @TIME.