In a 2014 national survey, the number of kids with autism spectrum disorder (ASD) appeared to skyrocket, jumping nearly 80 percent from 2011-2013 figures. But the increase is likely due to changes in the way parents and guardians were surveyed, according to a new report from the Centers for Disease Control and Prevention.

The new survey may capture a more accurate count of ASD cases, now estimated to be about 1 in 45 kids. In previous surveys, some of those cases may have been clumped into cases of other developmental delays, the authors report.

The prevalence of developmental disabilities, which includes ASD, other developmental delays, and intellectual disabilities, was unchanged between the 2011-2013 data and that of 2014. But the cases of developmental delays dropped between the periods almost as much as ASD cases rose.

The 2014 survey found that 2.24 percent of children aged 3 to 17 have autism (that’s about 1 in 45), while 2011-2013 survey data found an average prevalence of 1.25 percent (or 1 in 80).

Meanwhile, the prevalence of other developmental delays decreased nearly 67 percent from a prevalence of 4.84 percent to 3.57 percent in kids. And the prevalence of overall developmental disabilities stayed about the same with 5.75 percent in 2011-2013 and 5.76 percent in 2014.

The survey changes included adding a specific question about ASD, mentioning specific conditions within the definition of ASD, such as Asperger’s disorder, and reordering the questions. In past surveys, autism was included in a 10-condition checklist that followed a question about developmental delays.

The authors surmised that part of the old survey’s problem may have been the order, since ASD is a type of developmental delay. “After reporting their child’s ASD, parents likely assume (correctly, it is worth noting) that the next question about other [developmental delays] is asking about something other than ASD, and, therefore, should not be endorsed unless another non-ASD (and non-[intellectual disability]) developmental delay was diagnosed,” they wrote.

The new estimates are more in line with those of other CDC-supported ASD surveillance systems, such as the National Survey for Children’s Health, the authors report.