Objective. To determine the effect of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) on birth outcomes.
Data Source. The Child Development Supplement (CDS) of the Panel Study of Income Dynamics (PSID). The PSID provides extensive data on the income and well-being of a representative sample of U.S. families from 1968 to present. The CDS collects information on the children in PSID families ranging from cognitive, behavioral, and health status to their family and neighborhood environment. The first two waves of the CDS were conducted in 1997 and 2002, respectively. We use information on 3,181 children and their mothers.
Study Design. We use propensity score matching with multiple imputations to examine whether WIC program influences birth outcomes: birth weight, prematurity, maternal report of the infant's health, small for gestational age, and placement in the neonatal intensive care unit. Furthermore, we use a fixed-effects model to examine the above outcomes controlling for mother-specific unobservables.
Principal Findings. After using propensity scores to adjust for confounding factors, WIC shows no statistically significant effects for any of six outcomes. Fixed-effects models, however, reveal some effects that are statistically significant and fairly substantial in size. These involve preterm birth and birth weight.
Conclusions. Overall, the WIC program had moderate effects, but findings were sensitive to the estimation method used.