"This study investigates how maternal employment is related to the outcomes of 10 and 11 year olds after controlling for a wide variety of child, mother and family background characteristics. The results suggest that the mother's labor supply has deleterious effects on cognitive development, obesity and possibly risky behaviors such as smoking or drinking, while reducing behavior problems. These negative consequences are quite small for the average child, however, and usually restricted to relatively long maternal work hours. Less intensive employment is often associated with favorable outcomes and labor supply after the first three years typically has little effect. By contrast, large adverse consequences are frequently obtained for advantaged' adolescents, with negative impacts predicted even for limited amounts of maternal labor supply and for work during the child's fourth through ninth year"--National Bureau of Economic Research web site.