Aging out of WIC and child nutrition: Evidence from a regression discontinuity design

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is the third largest food assistance program in the United States. Child participants lose WIC in the month following their fifth birthday. We use this exogenous program rule for identification and find diet quality declines nearly 20%, on average, for those who have yet to transition into kindergarten. Decreases are mainly driven by reduced consumption of healthier WIC-targeted foods. A quantile regression discontinuity approach reveals children prone to lower quality diets experience the largest decreases in diet quality, reaching nearly 30%, whereas those prone to higher quality diets experience no aging-out-of-WIC effects. There are no effects on calorie consumption, regardless of school attendance, indicating caregivers maintain diet quantity for children at the expense of diet quality. Policy implications include allowing children to stay on WIC until they enter kindergarten. We calculate back-of-the-envelope program costs over the next 5 years for such a "kindergarten-roll-off" WIC policy under current rules and newly proposed rules to realign WIC packages with the Dietary Guidelines for Americans. Under current rules, costs would average $112 million over the next 5 years (2024-2028), or about 2% of total program costs. Under proposed rule changes, kindergarten-roll-off costs would average $144 million per year, or 2.25% of total program costs.