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Why Are Autism Spectrum Disorders Increasing?

The Centers for Disease Control and Prevention (CDC) estimates that about 1 in 88 children has been identified with an autism spectrum disorder (ASD). This data comes from the Autism and Developmental Disabilities Monitoring (ADDM) Network, which estimated the number of 8-year-old children with ASDs living in 14 communities throughout the United States in 2008. This new estimate marks a 23% increase since our last report in 2009, and a 78% increase since our first report in 2007. Read the latest prevalence report.

Prevalence of ASDs per 1,000 Children. 2002: 6.6, 2006: 9.0, 2008: 11.3Why Are ASDs Increasing?

At CDC, we know that people want answers to what is causing this increase, and so do we. The reasons for the increase in the identified prevalence of ASDs are not understood completely. Some of the increase is due to the way children are identified, diagnosed, and served in their local communities, although exactly how much is due to these factors is unknown. Also, it is likely that reported increases are explained partly by greater awareness by doctors, teachers, and parents. To understand more, CDC will keep guiding and conducting research into what is putting our children at risk.

However, the data tell us one thing with certainty—more children are being identified as having ASDs than ever before and these children and their families need help.

Recent Findings

Pregnancy and Birth Factors

CDC researchers developed a model to estimate how changes in six pregnancy and birth factors might have contributed to the increase in ASD prevalence:

  • Preterm and very preterm delivery
  • Low and very low birthweight
  • Multiple birth
  • Cesarean delivery
  • Breech presentation
  • In vitro fertilization or other assisted reproductive technologies (ARTs)

The study found that it is very unlikely that any of the pregnancy and birth factors included in the study could have been responsible for such a large increase in ASDs from 2002 through 2006.

Cover: Workshop on U.S. Data to Evaluate Changes in the Prevalence of Autism Spectrum Disorders (ASDs)However, the model developed for this study will be useful for future research and can be used to assess other risk factor scenarios.

Evaluation Workshop

To provide a forum for sharing the latest information on ASD prevalence changes, CDC and Autism Speaks co-hosted the "Workshop on U.S. Data to Evaluate Changes in the Prevalence of Autism Spectrum Disorders." The workshop brought together scientists and stakeholders from the autism community to increase knowledge about ASD prevalence, to learn from other conditions, and to share ideas on how to move forward to better understand ASD trends.

Spotlight On: Dr. Yeargin-Allsopp

One person who has helped lay the foundation for CDC's study of ASDs is Dr. Marshalyn Yeargin-Allsopp. Dr. Yeargin-Allsopp is a Developmental Pediatrician, Medical Epidemiologist, and Chief of the Developmental Disabilities Branch at the CDC's National Center on Birth Defects and Developmental Disabilities. She is not only a leader in the field of autism but also a trailblazer in her own career choices.

Photo: Dr. Marshalyn Yeargin-Allsopp"I came from a community that convinced me I could do anything—to reach for the stars. That encouragement carried me a long way. At age five, I declared that I would someday become a physician and by age eight I had already landed upon pediatrics as my medical specialty of choice.

"Following the advice of my great-uncle Dr. Benjamin Mays, long-time president of Morehouse College and mentor to Dr. Martin Luther King Jr., I continued to pursue greater academic challenges in the hopes of being accepted into a competitive medical school. I was the first Black student to graduate from Sweet Briar College. In 1968, I then enrolled in Emory University School of Medicine where I was once again the first Black female student to graduate.

"After I graduated from medical school in 1972 I headed north to complete my pediatrics internship and residency training at Montefiore Hospital in New York City. After spending three years as a general pediatrician, I realized that many of the questions from the parents of the children I worked with were around development and behavior. Also at that time, I had just given birth to my first child. As a new mother, I started developing an awareness of how this miraculous process of development unfolds during early childhood. This professional and personal desire to know more about development and to make an impact on the lives of children, no matter what their level of ability, drew me to a fellowship in developmental pediatrics at the Rose F. Kennedy Center at the Albert Einstein College of Medicine.

"By coincidence, I met Dr. Godfrey Oakley in 1980, who at the time was Director of the Division of Birth Defects at CDC. He encouraged me to move to Atlanta to join the CDC and help expand CDC's work in developmental disabilities. I came to CDC in 1981 as an officer for the Epidemic Intelligence Service (EIS), a unique 2-year training program for health professionals interested in the practice of applied epidemiology. As a new EIS officer and as part of the Birth Defects Branch, my first assignment was to investigate whether the prevalence of developmental disabilities could be tracked using education records. To answer that question, I designed a pilot study to determine the prevalence of intellectual disability in Atlanta. This pilot study found that education records contained information that could indeed be used, in addition to health records, to estimate the prevalence of developmental disabilities. CDC then applied this surveillance method to the first population-based study of multiple developmental disabilities: the Metropolitan Atlanta Developmental Disabilities Study (MADDS).

"Based on the success of MADDS, CDC launched the Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) in 1991. Even today, MADDSP continues to use the basic surveillance methods my colleagues and I developed in the 1980s to track developmental disabilities in metropolitan Atlanta. MADDSP is also the model program for CDC's Autism and Developmental Disabilities (ADDM) Network, which has been tracking ASDs and other developmental disabilities using this same method for over a decade and released updated ASD prevalence estimates in March 2012. Looking back, I can see the steps that led from the pilot project on intellectual disability in metropolitan Atlanta to today's nationwide ADDM Network. But at the time when I was working on the pilot study, I never got a feeling that we were somehow pioneers in the field. I just knew it was something we needed to do to help communities in the here and now.

"Through all my years in the public health field, I have remained committed to my roots as a developmental pediatrician and have maintained my practice as medical director of an early intervention program in Atlanta since 1983. I've never lost my desire to be a doctor—as a doctor, I can do something that makes a difference in the life of a child or family that is immediate. This experience makes me a better scientist and puts passion into my work. I see that the work we do at CDC is not just about statistics—it's about helping children and families. I never forget that there's a child behind every number."

More Information

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  • Page last reviewed: April 16, 2012
  • Page last updated: April 16, 2012
  • Content source:
    • Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs
    • Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs
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