Effects of WIC on Birth Outcomes: Evidence from Newly Digitized Data from the National Archives

This paper examines the effect of nutrition—delivered during pregnancy via the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC)—on infant health. We contribute to the literature by adding new data on WIC rollout from the National Archives, employing novel methods, investigating new mechanisms, and analyzing previously unexplored infant outcomes, including the distribution of birth weight. We find robust evidence that access to WIC in a woman’s county of residence by the start of their second trimester led to a reduction in the probability of an infant being of low birth weight and to a higher average birth weight, with larger in magnitude effects for infants with Black mothers than for those with White mothers. Our results suggest a lower bound for treatment-on-the-treated effects for low birth weight of -0.9 percentage points and for birth weight of around 33 grams for infants with Black mothers, both economically significant. For White mothers, the effects on low birth weight are much smaller in magnitude and statistically insignificant. These findings show WIC reduced overall disparities between Blacks and Whites in low birth weight by 3.6 percent.