Malnutrition in children, defined as a child who is more than 2 standard deviations below the norm for height- or weight-for-age, is a pervasive, population-wide problem in low- and middle-income countries. Malnutrition is associated with increased infant mortality and delayed neurocognitive development. A recent pooled analysis of more than 30 longitudinal cohort studies demonstrated that the conditions mothers lived in during pregnancy, and their access to adequate nutrition, was a major factor in the subsequent growth and health of their children. We review here this analysis and the hypothesis that interventions to address childhood malnutrition need to start before birth and continue throughout the critical first 1,000 days of life.