Does Greater Exposure to WIC Affect Maternal Behavior and Improve Infant Health? Evidence from the Pregnancy Nutrition Surveillance System

Recent analyses have reached differing conclusions on how effectively the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) improves infant health. We use 1996–2003 data from North Carolina’s Pregnancy Nutrition Surveillance System to address limitations in previous work. With information on the mother’s timing of WIC enrollment, we test whether greater exposure to WIC is associated with less smoking, greater weight gain, and better birth outcomes. Our results suggest that much of the often-reported association between WIC and lower rates of preterm birth is likely spurious, the result of gestational age bias. We find at best modest effects of WIC on fetal growth, but no association between WIC and smoking. A series of falsification tests provide additional evidence that the robust association between WIC and preterm birth from observational studies is likely specious. Does Greater Exposure to WIC Affect Maternal Behavior and Improve Infant Health? Evidence from the Pregnancy Nutrition Surveillance System