An infant’s risk of developing autism could be determined by looking for problems in the placenta at birth, scientists revealed today. Researchers at Yale University in New Haven, Connecticut, and the University of California in Davis say their findings will allow for earlier diagnosis and treatment for the developmental disorder. One in 100 Britons are estimated to have autism, while one out of 50 children are diagnosed with it in the U.S. each year - but this diagnosis is usually made when the children are aged three or four. This causes problems because the best chance for intervention is when the brain is most responsive to treatment in the first year of life, according to the researchers at both universities. Dr Harvey Kliman of the Yale School of Medicine and scientists at the MIND Institute of UC Davis have studied abnormal placental folds and abnormal cell growths known as trophoblast inclusions. The scientists have found that these are key markers to identify newborns who are at risk for autism. Dr Kliman and his team examined 117 placentas from infants of at-risk families - those with one or more previous children with autism. The at-risk placentas were compared to 100 control placentas. The at-risk placentas had 15 trophoblast inclusions, while none of the control placentas had more than two, according to the findings published today in the Biological Psychiatry journal. Dr Kliman said a placenta with four or more trophoblast inclusions suggests an infant will have a 97 per cent probability of being at risk for autism. Until now the best early indication of autism risk has been family history – with couples having a child with autism being nine times more likely to have another child with the disorder. Dr Kliman said: ‘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. ‘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.’