Autism risk among infants can be identified by looking at their placenta, researchers at the Yale School of Medicine and the MIND Institute at the University of California, say.
This may help doctors to intervene early.
For the study, senior author and a Yale researcher, Dr Harvey Kliman, and his colleagues analysed abnormal folds in the placenta. They also studied cell growths known as trophoblast inclusions. These proved as effective biomarkers to predict which children were at risk of autism.
The researchers observed 217 placentas; 117 from infants born to families who had children with autism and 100 control placentas. Infants from the autism-risk families were found to be nine times more likely to be detected with autism compared to others.
Around 15 trophoblast inclusions were found in some infants from the families with autism risk, which were extensively more than the control placentas, which did not have more than two inclusions.
The study revealed that a placenta with just four trophoblast folds is linked to a 96.7 percent chance of the newborn of developing autism.
However, the researchers do not know the connection between inclusions and the risk of developing autism in an infant.
"At birth we have a tool now that can tell us who's at risk and who isn't at risk for autism," said Dr Kliman. "This gives us the opportunity to intervene at a time when the brain is most plastic and able to transform."
In almost four decades the number of autistic children in the US has gone up tremendously. In 1975, only one out of 5,000 children was diagnosed with autism whereas in 2013, one in every 50 children is autistic.
Mothers suffering from obesity, nutrition, weight gain and diabetes, and those who are exposed to hormone disrupting chemicals, are likely to have babies with autism.
