WIC also promotes the initiation of breastfeeding and supports the continuation of breastfeeding among women who choose to breastfeed. In the early 1990s, Mathematica conducted the landmark WIC-Medicaid study (WM-I) which assessed the impact of prenatal participation in WIC on birth outcomes and Medicaid costs.

In the decades since WM-I was conducted, much has changed in both the WIC and Medicaid programs. For example, both programs have expanded dramatically and are serving larger segments of the low-income population; Medicaid income-eligibility thresholds are substantially higher today than at the time of WM-I; there are many more maternal and child health programs that target low-income pregnant women; and comprehensive changes to WIC’s supplemental food packages, which have the potential to improve the dietary patterns, breastfeeding status, and health behaviors of program participants, were implemented in 2009.

Because of these and related changes in the participation and policy environments for both WIC and Medicaid, the U.S. Department of Agriculture’s Food and Nutrition Service (FNS) awarded a contract to Mathematica to conduct the FNS WIC-Medicaid Study II (WM-II). The study will use linked administrative data from WIC, Medicaid, and vital records agencies to conduct two separate analyses: (1) the prenatal analysis will examine the associations between WIC participation during pregnancy and birth outcomes, health care utilization and costs, maternal behaviors, and maternal risk factors; and (2) the children’s analysis will examine the associations between child WIC participation and health care utilization and costs.

The first phase of the study is a feasibility assessment focused on two states (Oklahoma and Missouri). If the results of the feasibility assessment suggest that a rigorous evaluation of the relationships between WIC participation and outcomes of interest is feasible, FNS may elect to expand WM-II to include up to five additional states. The first phase of the study also included a comprehensive review of relevant recent research.