Children who have an older sibling with autism are much more likely to have the disorder than previously thought, according to a study in the journal Pediatrics.
The study, performed at UC Davis' M.I.N.D. Institute, studied 664 babies at 12 sites in the United States and Canada and found that males who had a sibling with autism were 26 percent more likely to develop it by 3. The same was true in 9 percent of girls. Boys tend to develop autism spectrum disorder in higher numbers than girls, for reasons not yet understood.
Overall, 132 babies were diagnosed with autism. "We were all a bit surprised and taken aback about how high it is," lead study author Sally Ozonoff, a psychiatry and behavioral sciences professor at the UC Davis institute, told The Associated Press.
According to the L.A. Times' story, researchers have long known that autism runs in families, but estimates on the risk for newborns have been pegged at 3 percent to 10 percent.
A baby who has more than one sibling with autism has an even greater chance of developing the disorder -- 32 percent. "I have seen families with five kids with autism," Yale University autism expert Dr. Fred Volkmar told the newspaper.
The researchers said the results shouldn't alarm parents of autistic children, but that the study is meant to further educate them. TIME.com's story says parents of an autistic child who want to have more children should work with their pediatricians to "step up developmental surveillance of future babies."
"These babies should potentially be treated differently than other infants," says Ozonoff. At a typical "well baby" check-up for a healthy infant, doctors often ask general questions such as, How is she doing? For babies who have older siblings with autism, doctors should be more specific, inquiring about eye contact, babbling, smiling at others and playing peek-a-boo — all developmental milestones whose absence could be worrisome.
If you're the parent of an autistic child, I'd like to hear your thoughts about this research. Please leave a comment below.