Changes in prevalence of parent-reported autism spectrum disorder in school-aged U.S. children: 2007 to 2011-2012.

The results of the cohort analyses increase confidence that differential survey measurement error over time was not a major contributor to observed changes in the prevalence of parent-reported ASD. Rather, much of the prevalence increase from 2007 to 2011-2012 for school-aged children was the result of diagnoses of children with previously unrecognized ASD.