The Epidemiology Project of the University of California-Davis Center for Children's Environmental Health (CCEH) will build upon its discovery of immunologic and molecular biomarkers specific to children with autism found in 2-5 year olds enrolled in the CHARGE (Childhood Autism Risks from Genetics and Environment) Study. As one of three interrelated research projects, this study will assess the stability of these immunologic markers over time. It will also test whether children with autism can be distinguished from those without autism by markers of immune dysregulation (at birth as well as post-diagnosis) and by prenatal, immunologically relevant events and exposures. The study aims to determine if children with and without autism differ with regard to exposures, body burdens, and excretion of xenobiotics, including metals, pesticides, and other pollutants (i.e., PBDE's). The transcriptional genomic profiles of children with and without autism will also be analyzed. Finally, a study tracking women at high risk for giving birth to a child with autism will follow them from early pregnancy until the child is three years old. The overall goal of the project is to determine early predictors of autism, whether they be immunologic, genomic, or environmental.