(RxWiki News) Autism runs in families, past research has shown. But even when a family risk is known, children are not usually diagnosed with autism until they are toddlers.
A recent study, however, has found a method that might help establish a baby's risk of autism at birth.
This study found that the placentas of women who already had at least one child with autism were much more likely to have certain abnormal creases.
The number of creases in a woman's placenta appears to predict how high a child's risk of developing autism might be.
"Attend all prenatal appointments."
The study, led by Cheryl K. Walker, MD, of the Department of Obstetrics and Gynecology at the University of California, Davis, investigated whether placenta abnormalities were risk factors for autism.
The researchers examined the placentas of 117 babies born to families participating in a study group called the Markers of Autism Risk in Babies–Learning Early Signs.
These families already had one or more child with an autism spectrum disorder, and past research has shown that having a sibling with autism increases the risk of developmental disorders in other children in the family.
The researchers also examined 100 placentas from women who gave birth to their babies at full term and without any complications. These women all had other children who were typically developing.
The researchers specifically looked for abnormal folds, or creases, in the major cell type of the placenta, called trophoblasts.
These abnormal creases are called trophoblast inclusions.
The researchers found that the placentas from the families with autism were eight times more likely to have two or more trophoblast inclusions compared to the placentas from women with only typically developing children.
The placentas from the families with autism had up to 15 trophoblast inclusions, but none of the placentas from the control families had more than two of these abnormalities.
In fact, 92 percent of the placentas from the women with no autistic children had only one trophoblast inclusion or none at all.
The researchers calculated that a placenta with four or more of these abnormalities predicted the baby had a 74 percent probability of being at risk for autism.
Identifying these abnormalities in the placenta "has the possibility of identifying newborns at risk for autism spectrum disorders who might benefit from targeted early interventions aimed at preventing or ameliorating behavioral symptoms and optimizing developmental outcomes," the researchers wrote.
The researchers looked for links between trophoblast inclusions and other pregnancy complications, including pre-eclampsia, gestational diabetes or high blood pressure, but they found none.
There was also no link between these placental abnormalities and the pregnancy week when the baby was born.
The study was published April 25 in the journal Biological Psychiatry. The research was funded by the National Institutes of Health, the US Environmental Protection Agency, the MIND Institute at the University of California, Davis and the Yale University Reproductive and Placental Research Unit. The authors reported no conflicts of interest.
