Note: This study was published in 2011. Since that time, updated statistics have been published. The Centers for Disease Control & Prevention (CDC) published new data on March 30, 2012, showing that 1 in 88 children -- or 1.13 percent of U.S. children -- has been diagnosed with autism spectrum disorder (ASD).
About 1 in 110 U.S. children have been diagnosed with an autism spectrum disorder (ASD), and children who have an older sibling diagnosed with ASD are more likely to receive a diagnosis. In the international study, "Recurrence Risk for Autism Spectrum Disorders: A Baby Siblings Research Consortium Study," published in the September 2011 issue of Pediatrics (published online Aug. 15), researchers calculated the risk of recurrence among siblings is substantially higher than previously thought.
Study authors monitored 664 infants with an older biological brother or sister with ASD from early in life to 36 months. Although past studies estimated the ASD recurrence risk between 3 percent and 10 percent, this study found that the overall risk was 18.7 percent and even higher in families with more than one affected sibling, approximately 32 percent. Male infants experienced nearly three times the risk of female infants, 26 versus 9 percent.
Neither parental age, gender of the sibling, functioning level of the sibling, or birth order, was a significant predictor of ASD outcome. Study authors suggested that this knowledge can impact future genetic screening and family planning decisions.
