Confronting social disparities in child health: a critical appraisal of life-course science and research.

The utility of the life-course framework to address disparities in child health is based on its ability to integrate the science of child development with the requirements of effective and just public policy. I argue that the life-course framework is best assessed in a historical context and through 4 essential observations. First, early genetic and environmental interactions are complex and influence outcomes in different settings in very different ways. Second, these early-life interactions are themselves subject to considerable later influences and, therefore, may not be highly predictive of later outcomes. Third, the etiologic nature or timing of early-life interactions does not, per se, determine if their life-course effects are amenable to later interventions. Fourth, a highly deterministic view of early-life interactions is not supported by the science and can generate counterproductive approaches to research and policy development. Finally, an alternative approach is proposed on the basis of a "human-capacity" model of the life course that connects the search for underlying basic mechanisms with a policy-based examination of the comparative effectiveness of influences at different developmental stages. This approach suggests an expanded research and policy agenda that might be more capable of generating urgently needed strategies for reducing disparities in child health. Such an approach could ultimately define more comprehensively the power and limits of life-course effects in shaping the social distribution of health outcomes in the real world.