Is WIC effective in improving pregnancy-related outcomes? An empirical reassessment

This study provides new evidence on how prenatal WIC participation influences pregnancy-related outcomes, using a large dataset of Medicaid mothers with two or more singleton births. Our analysis suggests there is negative selection by maternal unobserved factors even with a relatively homogenous sample and a rich set of observed characteristics. The conservative estimates from multiple regression which doesn't address maternal unobserved heterogeneity already demonstrate beneficial effects on a range of outcomes. The concern of mis-specification or extrapolation in the linear model is also ruled out. Controlling for the mother fixed effects, we find more statistically significant estimates which are usually larger in size. The within-mother estimates are robust in a series of sensitivity checks especially multiple inference adjustments. Overall, we find WIC does work to improve infant health and maternal health behaviors as well as reduce usage of costly maternity care.