Autism seems to have a powerful genetic component, but a family history of the disorder isn't the whole story. The circumstances of a baby's birth may also predispose a child to developing autism, says a new study. Babies who come into the world after a difficult delivery, who have to be coaxed or sometimes pulled out of the birth canal, who have gotten tangled in the umbilical cord or whose first days are characterized by feeding problems, anemia or jaundice, these children face higher odds of developing autism than those whose births were more uneventful, says the study, published Monday in Pediatrics.
But a big head, high birth weight and a mom who got anesthesia during childbirth don't appear to raise the risk that a child will develop autism, adds the study.
Epidemiologists from Harvard University and Brown University conducted the "meta-analysis," which sorted through and combined the results of 60 studies that explored autism prevalence as a function of many birth and neonatal factors. Such analyses help discern how strong the links are between autism and each of those factors and allows researchers to rank how powerfully different factors can influence the risk of developing a given disorder. The same group of researchers established in 2009 that advanced maternal and paternal age was a strong prenatal risk factor for autism, as was a mother's bleeding during pregnancy and gestational diabetes.