Modeling environmental influences on child growth in the MAL-ED cohort study: opportunities and challenges.

Although genetics, maternal undernutrition and low birth weight status certainly play a role in child growth, dietary insufficiency and infectious diseases are key risk factors for linear growth faltering during early childhood. A primary goal of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) study is to identify specific risk factors associated with growth faltering during the first 2 years of life; however, growth in early childhood is challenging to characterize because growth may be inherently nonlinear with age. In this manuscript, we describe some methods for analyzing longitudinal growth to evaluate both short- and long-term associations between risk factors and growth trajectories over the first 2 years of life across 8 resource-limited settings using harmonized protocols. We expect there will be enough variability within and between sites in the prevalence of risk factors and burden of linear growth faltering to allow us to distinguish some of the key pathways to linear growth faltering in the MAL-ED study.