More Evidence Preterm Birth May Raise Autism Risk
But researchers detect lower rate than previously reported
By Amy Norton
THURSDAY, Jan. 21, 2016 (HealthDay News) -- According to a new study, very premature infants may have an increased risk of being diagnosed with autism by age 4, although the research questions just how high the odds are.
The Australian study, published online Jan. 21 in Pediatrics, found that just under 2 percent of tiny preemies were later diagnosed with autism between 2 and 4 years of age.
That prevalence, the researchers say, is lower than what's been seen in past studies -- where figures have ranged from roughly 4 percent to 13 percent.
They also said there are reasons to trust the reliability of their findings. This study is one of the few to directly evaluate children, rather than using parent questionnaires, said lead researcher Margo Pritchard, a professor of neonatal nursing at Australian Catholic University, in South Brisbane.
"What we found is that being born very preterm is a risk factor, which is consistent with previous studies," Pritchard said. "But when diagnostic rigor is applied, using direct assessment, the rate of autism is lower than reported in other studies."
However, Dr. Paul Wang, senior vice president of medical research for the nonprofit organization Autism Speaks, said it's not clear what to make of the lower prevalence.
Studies differ in their methods, and some have followed children for longer periods -- to age 8 and beyond -- so it's hard to know which estimates are closer to the truth, Wang said.
Instead, he saw the new findings as further support for the overall picture. "Prematurity and low birth weight are risk factors for autism," Wang said.
He also stressed, however, that there is no single contributing factor to autism spectrum disorder -- a developmental disorder thought to affect one in 68 children in the United States, according to the U.S. Centers for Disease Control and Prevention.
Autism is complex, Wang said, and the mix of causes varies from one child to the next. But in general, experts believe it starts with a genetic vulnerability, in combination with certain environmental exposures at a critical point in development -- particularly in the womb.