Early childhood development interventions (ECDIs) have the potential to bring about wide ranging human capital benefits for children through to adulthood. Less is known, however, about the potential for such interventions to improve population health. The aim of this study was to examine the evidence for child health effects of centre-based preschool intervention programs for healthy 4 year olds, beyond the preschool years. Medline, Embase, ERIC, Psych Info, Sociological Abstracts, the Cochrane Library, C2-SPECTR and the Head Start database were searched using terms relating to preschool and health from 1980 to July 2008, limited to English language publications. Reference lists and the journal Child Development were hand searched for eligible articles missed by the electronic search. There were 37 eligible studies identified. The reviewed studies examined a range of interventions from centre-based preschool alone, to interventions also including parenting programs and/or health services. The study populations were mostly sampled from populations at risk of school failure (76%). Only eight of the 37 studies had a strong methodological rating, 15 were evaluated as at moderate potential risk of bias and 14 as at high potential risk of bias. The review found generally null effects of preschool interventions across a range of health outcomes, however there was some evidence for obesity reduction, greater social competence, improved mental health and crime prevention. We conclude that the great potential for early childhood interventions to improve population health across a range of health outcomes, as anticipated by policy makers worldwide, currently rests on a rather flimsy evidence base. Given the potential and the increasingly large public investment in these interventions, it is imperative that population health researchers, practitioners and policy makers worldwide collaborate to advance this research agenda.
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