Background: Preterm birth is a known risk factor for infant development but it is less clear whether fetal growth restriction (FGR) and early term birth between 37 and 39 weeks gestation are associated with risks for infant development. Aims: This study investigated risk factors for adverse developmental outcomes at 12 months of age in a population-based birth cohort. Study design: Cohort study. Subjects: Participants in the Raine Study, which recruited 2900 women at 18 weeks of gestation (Gen1) and followed up infants longitudinally (Gen2). At 12 months, 1773 mothers provided developmental data for their infants. Outcome measure: The Ages and Stages Questionnaire (ASQ) was used to measure gross and fine motor, communication, adaptability and personal social development. Multivariate logistic regression analyses were used to estimate associations between FGR, gestational age, sex, breast feeding, parental age, socioeconomic factors and developmental delay at 12 months of age as measured with the ASQ. Results: The risk of any delay at 12 months of age, as well as gross motor, fine motor and adaptive delay, was slightly increased for infants born FGR. Preterm and early term birth and male sex were associated with poorer development at 12 months. Breast feeding was protective of developmental status. Conclusions: Developmental assessment using the ASQ of infants with FGR was mostly comparable to those born without FGR at 12 months, although finer-grained neurobehavioural assessments may yield capacity for earlier identification of developmental risk. Our data provide weight to the argument that surveillance of early term infants could enable earlier intervention for children at risk.