Maternal work hours and childhood obesity: Evidence using instrumental variables related to sibling school eligibility

This study exploits plausibly exogenous variation derived from the youngest sib-ling’s school eligibility to estimate the effects of maternal work on the weight outcomes of older children. We first show that mothers’ work hours increase gradually along both the extensive and intensive margins as the age of the youngest child rises, whereas mothers’ spouses’ work hours do not appear to be responsive. We develop an instrumental-variables model that shows that mothers’ work hours lead to larger increases in children’s body mass index z-scores and probabilities of being overweight/obese than those identified in previous studies. Subsample analyses find that the effects are concentrated among advantaged households.