Identification of early signs of autism is a critical goal for research. This study will examine fetuses of mothers who have older children with autism spectrum disorder (ASD) in order to identify signs of autism in the prenatal and newborn periods. The study will investigate fetal movement and heart rate in response to social and non-social stimuli in pregnant mothers who have an older child with an ASD (high risk fetuses) as compared to mothers who have older children with typical development (low risk fetuses). Research has demonstrated that fetal responses to stimuli are predictive of later behavior and temperament, and that fetuses can discriminate familiar voices (i.e., respond differentially to social stimuli). This research is relevant to both early identification and intervention for children with autism. By identifying atypical behavioral and reactivity patterns in the fetal and newborn periods in infants at risk for autism, this research will aide in the development of more sensitive and specific screening and diagnostic tools for use in infancy.