The Dynamics of Prenatal WIC Participation and the Role of Past Participation

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides food vouchers, nutritional counseling, and health care referrals to low-income pregnant and breastfeeding women and their young children. This paper uses non-parametric and parametric duration models to study the factors that influence the timing of prenatal WIC participation among eligible women. The estimates show that black and Hispanic women, women with low levels of education, women who participate in other welfare programs and who have no insurance, and women who are overweight participate in WIC earlier than others. Thus, there appears to be negative selection on observables across a number of dimensions. The model is extended to allow past WIC participation to influence current WIC participation, and past participation is found to be the most important determinant of current participation. This result suggests that policies reach out to women who have not received WIC before may be especially beneficial. Finally, policy simulations show that recent policy changes requiring income documentation while also making recipients of other programs automatically eligible for WIC have off-setting effects with a small net increase in participation.