How many American children have autism? The U.S. government answers that question at least three different ways and says the latest estimate — 1 in 40 kids — doesn't necessarily mean the numbers are rising.
The new number, published Monday in Pediatrics , is from one of three periodic surveys the government uses to assess autism rates. It's higher than a different survey's estimate published earlier this year, but the surveys use different methods and measure different populations of kids so the results aren't really comparable.
Because there's no medical test, "autism spectrum disorder is a particularly challenging condition to track," government researchers wrote in the Pediatrics report.