METHODS: Participants included∼ 8000 families from the Growing Up in Ireland
longitudinal infant cohort, who were identified from the Child Benefit Register and randomly
selected to participate. Parent and teacher reports and standardized assessments were
used to collect information on children's problem behaviors, expressive vocabulary, and
cognitive abilities at age 3 and 5 years. Breastfeeding information was collected via
maternal report. Propensity score matching was used to compare the average treatment …