Interpreting the WIC debate.

Journal of Policy Analysis and Management, Vol. 24, No. 4, 691–701 (2005) © 2005 by the Association for Public Policy Analysis and Management Published by Wiley Periodicals, Inc. Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/pam.20133 The editors of JPAM have asked us to help readers make sense of the competing claims about the efficacy of the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) on pregnancy and birth outcomes that have appeared in the journal over the past three issues: The paper by Marianne P. Bitler and Janet Currie in JPAM, 24(1), (hereafter BC) argues that “WIC works”; the paper in this issue by Ted Joyce, Diane Gibson, and Silvie Colman (hereafter JGC), which—at the risk of oversimplifying a bit—argues that “WIC doesn’t work”1; and the comment by BC. We were chosen for this task in part because we are outsiders to the WIC debates, although the neutrality that comes as a benefit of being outsiders also entails some cost in terms of our immersion in the full history of the WIC literature. As a result we focus our attention here on understanding the sources of disagreement between the recent JPAM papers, both of which improve in a variety of ways upon previous research. Our goal is to help readers reconcile apparently conflicting papers operating at the frontier of the WIC evaluation literature. The second section of our essay focuses on what is arguably the main source of disagreement between BC and JGC: the plausibility that WIC could theoretically influence preterm birth rates. Joyce and colleagues argue that randomized clinical trials (RCTs) and other evidence from the medical literature rule out the possibility that nutritional programs could have an effect on preterm births, and by extension, that the only outcomes plausibly subject to a causal effect from WIC are birth outcomes conditional on gestational age (for example, infants born small for their gestational age, or SGA). Evidence that WIC is associated with outcomes that should not be affected by the program under JGC’s working hypothesis—such as preterm births—raises fundamental questions in their view about whether any of these estimates are successful in identifying the causal impacts of WIC itself rather than selection effects. In our view, there is currently more uncertainty within the medical literature than JGC suggest concerning the potential effects of nutritional and other health interventions on preterm births. Although the existing clinical evidence of a beneficial effect of isolated prenatal interventions on preterm births isn’t very good, weak evidence about the efficacy of prenatal care is fundamentally different from good evidence that prenatal care is ineffective. On the basis of existing clinical research, there seems to be no compelling reason to exclude some birth outcomes from consideration in WIC evaluation studies.