The authors study the effects of prenatal receipt of nutritional and educational services provided by the Supplemental Nutrition Program for Women, Infants, and Children (WIC) on birth outcomes. Their identification strategy consists of two elements: (1) identifying families in a very tight income range surrounding the WIC eligibility threshold; and (2) exploiting a policy change that differentially influenced the WIC takeup rates of the families on each side of the eligibility threshold.

They conduct this analysis by merging three large statewide administrative datasets from Florida concerning all births during the period 1997–2001. The authors match the birth records of infants and the school records of their older siblings in order to relatively precisely identify “marginally eligible” and “marginally ineligible” families that are very similar in their observable characteristics. They find that WIC participation has no effect on mean birth weight and gestational age, but substantially reduces the likelihood of adverse birth outcomes, e.g. birth weights below 2500g.