Pinning Down Risk Factors for Autism Elusive: Study

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NEW YORK (Reuters Life!) - Research has hinted that various factors around the time of birth may raise a child's risk of autism later in life, but there is still too little evidence to point to specific culprits, a U.S. study said.Experts have long believed that genes play a key role in autism risk, but a U.S. study released last week found that genes appeared to explain a much smaller portion of the risk than previously suggested.The latest study, a review published in Pediatrics of 40 previous studies, found that factors including low birth weight, fetal distress during labor and signs of "poor condition" in the newborn, such as problems with breathing or heart rate, have been linked to the risk of autism."There is insufficient evidence to implicate any one perinatal or neonatal factor in autism etiology, although there is some evidence to suggest that exposure to a broad class of conditions reflecting general compromises to perinatal and neonatal health may increase the risk," wrote Hannah Gardener, a researcher at the University of Miami who led the study when she was at the Harvard School of Public Health.The current findings, Gardener said, underscore the importance of continuing to study which environmental factors -- whether before, during or after birth -- may act in concert with genetics to cause autism.Twin studies have shown that when one identical twin develops autism, the other has a high likelihood of being affected as well. …