CDC: Autism Rates in U.S. Children Continue to Rise — to 2.76%, or 1 in 36

A 4-fold increase in childhood autism prevalence measured by CDC ADDM Network over 20 years
4.3% of U.S. boys are now estimated to have autism

The U.S. Centers for Disease Control and Prevention announced the latest findings from the Autism and Developmental Disabilities Monitoring Network (ADDM), for surveillance year 2020. Despite the delays and clinical disruptions caused by the Covid pandemic, the prevalence of autism among both 8 year-olds and 4 year-olds continued to climb. Highlights:

8 Year-Olds (born 2012)

  • Over 20 years of ADDM surveillance the autism rate has climbed dramatically, more than 4-fold: now 1 in 36, for children born in 2012, compared to 1 in 150 for those born in 1992. Put another way, from .67% to 2.76% 

  • These estimates are higher than previous ADDM Network estimates during 2000–2018; prevalence in the 2018 surveillance was 1 in 44

  • ASD was 3.8 times as prevalent among boys as among girls (4.3% of boys versus 1.14 % of girls)

  • Across all 11 ADDM sites, ASD prevalence for 8 year-olds ranged from 2.31% in Maryland to 4.49% in the California region analyzed (part of one county in metropolitan San Diego)

  • Among the 4,165 (66.7%) children with ASD with information on cognitive ability, 37.9% of them were classified as having an intellectual disability (ID) (an increase from two years prior), 23.5% had borderline ID (an increase from two years prior), and 38.6% had no ID (a decrease from two years prior)

  • For the first time among children aged 8 years, the prevalence of ASD was lower among White children than among other racial and ethnic groups, reversing the direction of racial and ethnic differences in ASD prevalence observed in the past

  • Black children with ASD were still more likely than White children with ASD to have a co-occurring intellectual disability

  • ASD prevalence was associated with lower household income at three sites, with no association at the other sites

  • For 2020, the ADDM Network included 11 sites (Arizona, Arkansas, California, Georgia, Maryland, Minnesota, Missouri, New Jersey, Tennessee, Utah, and Wisconsin) that monitored ASD prevalence. Each site selected a geographic area of its state to monitor ASD among childrenaged 8 years. Children included in this report were born in 2012 and lived in surveillance areas of the 11 sites during 2020.

  • The ADDM Network conducts active surveillance of ASD by using multiple sources of information within a community, including medical, education and service provider data

  • To be counted as ASD, staff reviewed documentation that they received 1) a written ASD diagnostic statement from a qualified professional, 2) a special education classification of autism (either primary exceptionality of ASD or an evaluation reporting criterion for autism eligibility was met) in public school, or 3) an ASD ICD code (ICD-9 codes between 299.00 and 299.99 or ICD-10 codes in the F84 range except for Rett syndrome) obtained from administrative or billing information. ASD-related diagnostic conclusions (including suspected ASD or ruled out ASD) were collected verbatim from evaluations and were reviewed and classified by ADDM Network staff with clinical expertise at each site.

4 Year-Olds (Born 2016)

  • A companion study also found a markedly higher overall prevalence of ASD among 4 year-olds than 2 years prior, with a rate of 2.15% — it was 1.7% in 2018

  • The 4 year-old ASD prevalence among boys was 3.23%, 3.1 times as high as among girls (1.04%)

  • Prevalence among 4 year-old girls surpassed 1% for the first time in ADDM Network surveillance (also observed among children aged 8 years for the first time)

  • For the 4 year-olds, 2020 prevalence was 24.3% higher among boys and 34.5% higher among girls than prevalence in 2018, but the male-to-female ratios were similar between years

  • Among children with data on intellectual ability, 48.5% of children with ASD met the surveillance case definition of having comorbid ID(range = 24.7% in California to 67.3% in Arkansas), which was similar to the 2018 data

  • ASD prevalence was higher among Hispanic, Black, and A/PI childrencompared with White and AI/AN children

Source: CDC ADDM data

When viewed over time, ADDM data do not support the oft-repeated notion that rates continue to climb simply because the system is capturing an increasing number of mild cases that would not have been detected in prior years. Data indicate that the prevalence of cases with comorbid ID and borderline ID has increased markedly since this data was first collected in the 2008 surveillance year:

  • For those with ID, or IQ 70 and under, the population prevalence was .429% in 2008; in 2020 it more than doubled to 1.046%. 

  • For those with borderline ID, or IQs 71-85, the population prevalence was .271% in 2008; in 2020 it more than doubled to .649% in 2020.

  • For those with no ID, or IQs above 85, the population prevalence was .429 in 2008; it also more than doubled, to 1.06% in 2020.


    More information on the CDC ADDM Network here