A large body of literature evaluates the extent to which the Supplemental Program for Women Infants and Children (WIC) has accomplished the goal of improving nutritional well-being and health of low income families, but most studies have been based on research designs that compare program participants to non-participants. If selection into these programs is non-random, then such comparisons will lead to biased estimates of the program’s true effects. In this study, investigators use the rollout of the WIC program across counties to estimate the impact of the program on infant health.
Researchers find that the implementation of WIC lead to an increase in average birthweight and a decrease in the fraction of births that are classified as low birthweight. They find no evidence that these estimates are driven by changes in fertility, and back-of-the-envelope calculations suggest that the initiation of WIC lead to a ten percent increase in the birthweight of infants born to participating mothers.