The origins of early childhood anthropometric persistence

The rates of childhood obesity have increased dramatically in the last few decades. Non-causal evidence suggests that childhood obesity is highly persistent over the life cycle. However, little is known about the origins of this persistence. This paper examines the evolution of anthropometric measures from birth through primary school. We provide estimates of the causal effect of past anthropometric outcomes on future anthropometric outcomes (state dependence) and investigate the importance of time-varying and time-invariant factors in the dynamics of childhood anthropometric measures. We find that anthropometric measures are highly persistent from infancy through primary school. Moreover, most of this persistence is driven by time-invariant, unobserved factors that are determined prior to birth, consistent with the so-called fetal origins hypothesis. Thus, policy interventions designed to improve childhood obesity will only have meaningful, long-run effects if these time-invariant, unobserved factors are altered. Future research is needed to identify such factors, although evidence suggests that maternal nutrition may play an important role.