In other words, the condition was reported in 2.5% of children, representing an estimated 1.5 million kids ages 3 to 17.

A report released this year by the US Centers for Disease Control and Prevention estimated the prevalence at one in 59 children or about 1.7%, based on 2014 data.

“Prevalence is not growing that rapidly, although the CDC’s data suggests it is still growing,” Thomas Frazier, chief science officer of the advocacy organization Autism Speaks, said in an emailed statement. He was not involved in the new report.