Table 1.

Studies Addressing Selection Bias of WIC Participation in Breastfeeding

Public ation Year	First Author’s Last Name	Data	Study Period	Sample Size	Approach	Results
2005	Bitler	Pregnancy Risk Assessment Monitoring System (PRAMS) (19 states)	1992–1999	60,731	State-year fixed effect	+
2010	Jiang	Panel Study of Income Dynamics	1997	3,276	Propensity score	biased negative relations hip
2013	Martin-Anderson	Infant Feeding Practices Study II	2005–2007	785	WIC duration	−
2015	Metallinos-Katsaras	Massachusetts WIC Program	2001–2009	122,506	WIC duration	+
2016	Bullinger	Infant Feeding Practices Study II	2005–2007	3,029	IV (state-level grocery price index)	−
2016	Gregory	Infant Feeding Practices Study II	2005–2007	743	Propensity score	no negative
2017	Sonchak	South Carolina Birth Certificate Data	2004–2013	16,457	Maternal fixed effects	no negative
2017	Topolyan	Infant Feeding Practices Study II	2005–2007	2,616	WIC duration	−
2019	Li	National Health and Nutrition Examination Survey (NHANES)	2005–2014	4,308	Propensity score	−

+/−: Positive/negative relationship between WIC participation and breastfeeding