RESUMEN
Multiple birth is one of several perinatal factors associated with increased risk for autism spectrum disorder (ASD); however, complexity in its relationship to ASD symptoms and developmental functioning remains. The present study investigated perinatal risk factors for ASD, primarily focusing on birth status, within a large early intervention sample. In particular, the relationship between ASD, perinatal factors, and the effect of birth status on developmental functioning and ASD symptom severity were examined in youth with and without ASD classification who were born singly or were the product of a multiple birth. Overall, the presence of other perinatal risk factors, including prematurity, low birth weight, and advanced parental age, was primarily related to birth status and not to ASD classification, while severity of ASD symptoms and developmental impairments were primarily related to ASD classification and not to birth status. Study findings and implications for early screening of children with developmental delays are discussed.