No single cause of autism, research review concludes

July 12, 2011 Many factors of a child's birth and the condition of the newborn are linked to the future development of autism, but no single factor has been identified as the cause, a of forty previously published research studies concludes.

Autism refers to a cluster of neurological developmental disorders, ranging to mild and severe, that interfere the child's ability to adjust normally, including defects in normal communication and social interaction.

The systematic review, published in Monday's issue of , presented the results of a  of over sixty  and  risk factors associated with autism reported in the forty published studies. It identified sixteen that were significantly associated with autism. These included, , fetal distress during labor, "poor condition" of the newborn along with a low , , to the baby, and  of the mother during childbirth.

However, the review found that often these factors are linked; not occurring independently but in combination, making the effect of any one factor difficult to determine. Further, the conclusions of the studies often were in conflict with each other regarding the relationship of any single one of the factors to autism. The researcher concluded there was "insufficient evidence to implicate any one perinatal or neonatal factor in autism etiology." However, they said some evidence suggested the presence of "multiple neonatal complications may increase autism risk."

The review also ruled out some factors, finding some were not linked to autism such as the use during childbirth of,  or. High birth weight and large head circumference of the newborn were also discounted.

The researcher who headed the study, Hannah Gardener, who was at the at the time and is now at the, emphasized in an interview that parents should not worry if any one of the factors was present at the time of their child's birth.

She said, "There is no single strong cause of autism."

have concluded that there is a to autism and Gardener emphasized the importance of  the review's conclusions that point to the need for continuing study of how factors surrounding birth may interact with genetic factors to result in future autism in a child.