Analyzing a newborn's placenta will yield clues which can help diagnose the risk of the child developing autism, according to a report from Yale University.

Harvey Kliman and his team of researchers and collaborators at the Yale School of Medicine and the MIND Institute at the University of California, Davis, have found that abnormal placenta folds and abnormal cell growths called trophoblast inclusions are "key markers to identify newborns who are at risk for autism."

Data from the U.S. Centers for Disease Control and Prevention  indicates that one in 50 children are diagnosed with autism spectrum disorder in the U.S. each year. The Yale study notes that the diagnosis often comes after the children are already 3 or 4 years old.

"By then the best opportunities for intervention have been lost because the brain is most responsive to treatment in the first year of life," the Yale statement reports.

To complete the study, Kilman analyzed the placenta of 117 newborns from a group of families considered to be at -risk because they had already had at least one child born with autism.  Those placentas were compared with 100 control placenta collected from babies born in the same geographic area.

None of the control placenta had more than two trophoblast inclusions, whereas the at-risk placenta has as many as 15 trophoblast inclusions. According to Kilman, a placenta with four or more trophoblast inclusions conservatively predicts an infant with a 96.7% probability of being at risk for autism.

A couple with a child who has autism are nine times more likely to have another child with autism, according to the Yale report.

The good news to come from the findings is that families already at risk will have a better chance of employing early prevention strategies which may improve outcomes, according to the report.

"Regrettably couples without known genetic susceptibility must rely on identification of early signs or indicators that may not overtly manifest until the child's second or third year of life," said Kliman.

"I hope that diagnosing the risk of developing autism by examining the placenta at birth will become routine, and that the children who are shown to have increased numbers of trophoblast inclusions will have early interventions and an improved quality of life as a result of this test," Kliman said.

The findings are reported in the April 25 online issue of Biological Psychiatry.