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How many people are affected by autism spectrum disorder (ASD)?

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Researchers don't know exactly how many people in the United States have ASD.

The latest estimates suggest that:

  • About one out of every 88 children in the United States currently has autism.1
  • About 36,500 of every 4 million children born each year in the United States will have autism.2,3

The CDC is the government agency that studies how many people have autism and other diseases. Visit the CDC website for more information on how many people have ASD: http://www.cdc.gov/ncbddd/autism/data.html

Is ASD more common now than it was in the past?

More people than ever before are being diagnosed with ASD, but it is not clear why.

Some of this increase could be due to a broader definition of autism, better efforts in diagnosis, or greater awareness about symptoms. But researchers can't rule out the possibility that there has been a true increase in the number of autism cases.4,5,6,7,8

Who is at risk for ASD?

Research shows that some groups are at higher-than-normal risk for ASD:

  • Boys. Data show that boys are four to five times more likely than girls to have autism.9,10
  • Siblings of those with ASD.11,12 Among families that have one child with autism, there is a 2 % to 8 % chance that another sibling will have autism.13,14 This is much higher than in the general population.15 The chance is even greater if two older children in the family have autism.16
  • People with certain other developmental disorders. ASD commonly occurs with other disorders, such as Fragile X syndrome and tuberous sclerosis.17
  • Babies born extremely preterm (before 26 weeks into pregnancy).18
  • Children of older mothers and fathers.19

More research is needed to better understand why these factors increase autism risk.

Race, Ethnicity, and Autism

Current figures show that ASD occurs in all racial, ethnic, and social groups.

Autism is diagnosed more often in some groups than others.20,21 However, there is no clear evidence that any racial or ethnic groups are at greater risk for autism than are others.22


  1. Autism and Developmental Disabilities Monitoring Network Surveillance Year 2008 Principal Investigators, CDC. (2012). Prevalence of autism spectrum disorders - Autism and Developmental Disabilities Monitoring Network, 14 Sites, United States, 2008. MMWR Morbidity and Mortality Weekly Report:, 61(SS03), 1-19. Retrieved March 29, 2012, from
    http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6103a1.htm?s_cid=ss6103a1_w. [top]
  2. CDC. (2010). Autism Spectrum Disorders-Data & Statistics. Retrieved January 28, 2011, from
    http://www.cdc.gov/ncbddd/autism/data.html. [top]
  3. Brugha, T. S, McManus, S., Bankart, J., Scott, F., Purdon, S., Smith, J., et al (2011). Epidemiology of autism spectrum disorders in adults in the community in England. Archives of General Psychiatry, 68(5), 459-465. [top]
  4. Fombonne, E. (2001). Is there an epidemic of autism? Pediatrics, 107, 411-412. [top]
  5. Heussler, H., Polnay, L., Marder, E., Standen, P., Chin, L. U., & Butler, N. (2001). Prevalence of autism in early 1970s may have been underestimated [letter]. British Medical Journal, 323, 633. [top]
  6. Blaxill, M.. (2002). Any changes in prevalence of autism must be determined [letter]. British Medical Journal, 324, 296. [top]
  7. Chakrabarti, S. & Fombonne, E. (2001). Pervasive developmental disorders in preschool children. Journal of the American Medical Association, 285(24), 3093-3099. [top]
  8. Chakrabarti, S., & Fombonne, E. (2005). Pervasive developmental disorders in preschool children: Confirmation of high prevalence. American Journal of Psychiatry, 162(6), 1133-1141. [top]
  9. Autism and Developmental Disabilities Monitoring Network Surveillance Year 2006 Principal Investigators, CDC. (2009). Prevalence of autism spectrum disorders - Autism and Developmental Disabilities Monitoring Network, United States, 2006. MMWR Morbidity and Mortality Weekly Report, 58(SS10), 1-20. Retrieved January 28, 2011, from http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5810a1.htm. [top]
  10. Autism and Developmental Disabilities Monitoring Network Surveillance Year 2000 Principal Investigators, CDC. (2007). Prevalence of Autism Spectrum Disorders-Autism and Developmental Disabilities Monitoring Network, Six Sites, United States, 2000. MMWR Morbidity and Mortality Weekly Report, 56(SS01),1-11. Retrieved September 21, 2011, from http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5601a1.htm. [top]
  11. Risch, N., Spiker, D., Lotspeich, L., et al. (1999). A genomic screen of autism: evidence for a multilocus etiology. American Journal of Human Genetics, 65, 493-507. [top]
  12. Asherson, P. J., & Curran, S. (2001). Approaches to gene mapping in complex disorders and their application in child psychiatry and psychology. The British Journal of Psychiatry, 179, 122-128. [top]
  13. Micali, N., Chakrabarti, S., & Fombonne, E.. (2004). The broad autism phenotype: Findings from an epidemiological survey. Autism, 8, 21-37. [top]
  14. Ozonoff, S., Young, G. S., Carter, A., Messinger, D., Yirmiya, N., Zwaigenbaum, L., et al. (2011). Recurrence risk for autism spectrum disorders: a baby siblings research consortium study. Pediatrics, 128(3), e488-95. [top]
  15. Muhle, R., Trentacoste, S. V, & Rapin, I. (2004). The genetics of autism. Pediatrics, 113(5), e472-486. [top]
  16. Rutter, M. Genetic influences and autism. In: Volkmar, F. R., Paul, R., Klin, A., Cohen, D., eds. Handbook of Autism and Pervasive Developmental Disorders. 3rd ed. Vol 1. Hoboken, NJ: John Wiley & Sons; 2005:425-452. [top]
  17. Johnson, C. P., & Myers, S. M.; American Academy of Pediatrics Council on Children with Disabilities. (2007). Identification and evaluation of children with autism spectrum disorders. Pediatrics, 120(5), 1183-1215. [top]
  18. Johnson , S., Hollis, C., Kochhar, P., Hennessy, E., Wolke, D., & Marlow, N. (2010). Autism spectrum disorders in extremely preterm children. Journal of Pediatrics, 156(4), 525-531. [top]
  19. Grether, J. K., Anderson, M. C., Croen, L. A., Smith, D., & Windham, G. C. (2009). Risk of autism and increasing maternal and paternal age in a large North American population. American Journal of Epidemiology, 170(9), 1118-1126. [top]
  20. Autism and Developmental Disabilities Monitoring Network Surveillance Year 2008 Principal Investigators, CDC. (2012). Prevalence of autism spectrum disorders - Autism and Developmental Disabilities Monitoring Network, 14 Sites, United States, 2008. MMWR Morbidity and Mortality Weekly Report, 61(SS03), 1-19. Retrieved March 29, 2012, from http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6103a1.htm?s_cid=ss6103a1_w. [top]
  21. Mandell, D. S., Wiggins, L. D., Carpenter, L. A., Daniels, J., DiGuiseppi, C., Durkin, M. S., et al. (2009). Racial/ethnic disparities in the identification of children with autism spectrum disorders. American Journal of Public Health, 99(3), 493-498. [top]
  22. Fombonne, E. (2002). Epidemiological trends in rates of autism. Molecular Psychiatry, 7(suppl 2), S4-S6. [top]

Last Updated Date: 11/30/2012
Last Reviewed Date: 11/30/2012
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