Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) a population-based, prospective cohort study were used. We enrolled 14,541 pregnancies, and a 10% sample of these were dentally examined and measured at 61 months of age. Birthweight was obtained from medical records, and birth length and birthweight were assessed by trained ALSPAC measurers. A number of social and lifestyle factors were treated as potential confounding factors.