What to know
The Study to Explore Early Development (SEED) is a multi-year, multi-site study funded by CDC. It is one of the largest studies in the United States helping us learn more about autism spectrum disorder (ASD) and other developmental disabilities in preschool-aged children. One goal of SEED is to identify early behaviors and other factors related to the development of ASD symptoms that impact quality of life. Learning about these factors may shed light on how we can help children with ASD and their families.
About SEED 1, 2, and 3
Since the launch of SEED in 2007, CDC has conducted three phases of the study, known as SEED 1, 2, and 3. CDC has funded seven sites to conduct SEED. CDC, in Atlanta, serves as the eighth SEED site. Across all study sites, more than 6,500 families participated in SEED 1, 2, or 3, combined. This includes nearly 2,000 families with a child with ASD.
- California SEED: Kaiser Foundation Research Institute and the California Department of Public Health
- Colorado SEED: JFK Partners and University of Colorado School of Medicine, Anschutz Medical Campus
- Georgia SEED: The National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention
- Maryland SEED: Johns Hopkins University* and Kennedy Krieger Institute
*Johns Hopkins University also serves as the SEED biorepository center.
- Missouri SEED: Washington University at St. Louis
- North Carolina SEED: University of North Carolina at Chapel Hill
- Pennsylvania SEED: University of Pennsylvania School of Nursing and The Children's Hospital of Philadelphia
- Wisconsin SEED: The Board of Regents of the University of Wisconsin System
SEED research method
SEED 1, 2, and 3 used a case control method. This means that SEED actively looked for children with ASD and compared them with children in two other groups. These groups included children with other developmental delays or disabilities who were receiving education or health services, and children from the general population. All children were between 2 and 5 years of age when they enrolled in SEED.
The children with other developmental delays or disabilities and those from the general population were compared with children with ASD to see how they differ from one another.
During the study, parents answered questions about their family's medical history, including the health of mothers before, during, and after pregnancy. They completed questionnaires about their child's behavior and development. Families were also asked to let SEED summarize information from the mother and child's medical records, such as past diagnoses and medications prescribed by a doctor. Children had physical and developmental examinations by trained study clinicians. Finally, each parent and child were asked to give a small sample of saliva or blood.
What are we learning from SEED?
Some of the main findings from SEED include the following:
- There is not one cause of ASD; instead, the SEED study found several factors that were associated with the development of ASD, including the following:
- Pregnancy factors, such as infection with fever in the second trimester of pregnancy [Read summary]
- Mother and child conditions that involve the immune system attacking healthy cells, tissues, and organs (such as eczema and psoriasis) [Read summary]
- Environmental factors, such as the interaction between air pollution and neighborhoods with high poverty [Read summary]
- Pregnancy factors, such as infection with fever in the second trimester of pregnancy [Read summary]
- Children with ASD are more likely than other children to have developmental delays, gastrointestinal problems, and sleep problems, and to engage in wandering and self-harming behaviors.
- Contrary to recommendations, many children with ASD are given psychotropic medication to treat challenging behaviors before they receive behavior therapies. [Read summary]
What's next for SEED?
We will continue to learn more from this important study because analyses of SEED 1, 2, and 3 data are ongoing. We are also analyzing data from SEED Teen, a pilot study that followed children who participated in SEED 1 into adolescence, and SEED COVID-19 Impact Assessment, a survey of families of children who participated in SEED 3 to assess the impact of the COVID-19 pandemic. In 2023, the CDC launched SEED Follow-Up.
SEED Follow-Up expands upon SEED Teen to learn more about the services, supports, and needs of children with ASD as they mature, and their families.