The growing epidemic of childhood obesity is one of the most serious health concerns in the U.S. over the past decades. Obese children are known to suffer from physical, psychological, and developmental health problems, both in childhood and in adulthood. However, little is known about the possible causal mechanisms that are driving this increase in childhood obesity, especially in low income families, since established evidence is fuzzy and ambiguous.

Childhood obesity is generally explained by the imbalance between energy intake and energy expense. Numerous potential factors affecting energy imbalance such as food market change, environmental change, school policy change, and parental role change have been examined. Recent studies have suggested that increase in mother’s labor market participation has led to more childhood obesity since working mothers may have less time to prepare homemade meals and supervise and encourage their children’s physical activities.

The possibility that there is a causal link between maternal work and childhood obesity raises serious concerns regarding maternal labor market participation from low-income families for two reasons. First, the average childhood obesity rate is much higher among low-income families; and Second, social policies targeted at low-income families encourage mother’s labor market participation. For example, both the Earned Income Tax Credit (EITC) and the Temporary Aid for Needy Families (TANF) induce low-income mothers to enter the labor market. Our primary research question is to study whether social policies inducing mother’s labor market participation have unintentionally increased childhood obesity.  We find that previous studies have not offered a clear answer and also that further evidence, from theoretical and empirical studies, is required to shed more light on the questions raised in this debate.

To address these research questions, we adopt the Early Childhood Longitudinal Study, Kindergarten cohort of 1998-99 (ECLS-K) data sponsored by U.S. Department of Education. ECLS-K study followed 21,409 children from kindergarten through eighth grade and contained numerous measures of children’s physical health, i.e. Body Mass Index, dietary habits and physical activities; information about mother’s employment status and other household demographic indicators. Preliminary results indicate a positive association between mother’s work, measured by accumulated mothers’ work and current weekly work hours with children are in 1^st, 3^rd and 5^th grades, and child obesity. These relationships are stronger for mothers from high-income families while they are weak and statistically insignificant for mothers from families below the poverty line. We explain this outcome using a health capital production function of maternal hours spent with children. In this model, we argue that mothers from high-income families may have a steeper health capital production curve because they may have better knowledge and skills in child rearing. Hence, social programs targeted at low-income families which encourage mother’s labor force participation may not lead to childhood obesity.