Federal officials are releasing new data showing that the estimated number of U.S. children with autism has increased once again.

The Centers for Disease Control and Prevention said Tuesday that 1 in 31 children are on the autism spectrum.

The figures published in the CDC’s Morbidity and Mortality Weekly Report are based on information collected on 8-year-olds in 16 communities in 2022 through the CDC’s Autism and Developmental Disabilities Monitoring, or ADDM, network.

The findings represent an increase over the CDC’s 1 in 36 estimate, which was released in 2023. By comparison, in 2000, the rate was 1 in 150.

In the study, children were considered to have autism if they had ever been diagnosed in a developmental evaluation, if they were deemed eligible for special education due to autism or if they had an autism diagnosis under the ninth or tenth revisions of the International Classification of Diseases.

Autism rates varied considerably across the sites studied with a low of 1 in 103 children diagnosed in Laredo, Texas versus a high of 1 in 19 in California, which CDC researchers attributed to the level of available resources.

“Research has not demonstrated that living in certain communities puts children at greater risk for developing ASD,” the study states. “Differences in the prevalence of children identified with ASD across communities might be due to differences in availability of services for early detection and evaluation and diagnostic practices.

The CDC found that autism was more than three times as prevalent in boys compared to girls and was more common among minority children.

In cases where the researchers had access to information about cognitive ability, nearly 40% of the children with autism who were studied also had intellectual disability.

The CDC report also looked at children born in 2018 and found that they were more likely than their predecessors to be evaluated or identified as having autism by age 4, despite a hiccup during the early stages of the COVID-19 pandemic. Prevalence among 4-year-olds was estimated at 1 in 34 in the new report and the CDC pegged the median age of diagnosis at just under 4 years.

The updated autism prevalence estimate comes just days after U.S. Secretary of Health and Human Services Robert F. Kennedy Jr. promised President Donald Trump that he would identify the cause of what he dubbed the “autism epidemic” by September.

“The autism epidemic is running rampant,” Kennedy said in announcing the new data. “Autism is preventable and it is unforgivable that we have not yet identified the underlying causes. We should have had these answers 20 years ago.”

Autism advocates are disputing Kennedy’s characterization, arguing that the increase in prevalence reflects improved awareness, screening and diagnostics, particularly in underserved communities.

“This rise in prevalence does not signal an ‘epidemic’ as narratives are claiming — it reflects diagnostic progress, and an urgent need for policy decisions rooted in science and the immediate needs of the autism community,” the Autism Society of America said in a statement.