This pilot study will establish a new project called the Finnish Prenatal Study of Autism and Autism Spectrum Disorders (FiPS-A). The FiPS-A is based on the Finnish Maternity Cohort (FMC), which consists of virtually all births in Finland (N=1.1 million) from 1987- 2005. The investigators will use maternal medical and exposure history collected during pregnancy to examine if infection, hormonal abnormalities and smoking are related to an increased risk of autism in their children in a subset of these 1.1 million births. This study will also be able to identify potential early risk factors including improper growth and development before the child was diagnosed to assess whether these parameters can be included in early signs of autism. In addition to medical data, this project has the ability to analyze blood samples that were drawn during pregnancy in a random sample of children who are diagnosed with autism, and a random sample of children without autism, all of whom were in the national FMC cohort. What this means for people with autism: This project has the potential to become one of the largest epidemiological studies to investigate prenatal and perinatal risk factors in autism, including a large biomarker repository to isolate possible early prenatal risk factors. In addition to studying the longitudinal development of children who later develop autism, multiple environmental factors, including medical information from the mother and child, will be studied for further analysis.