摘要：Objectives. We assessed the effect of the new Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package, implemented in October 2009, on breastfeeding outcomes among a predominately Latina sample of WIC participants in Los Angeles County, California. Methods. We used data from 5020 WIC participants who were interviewed in a series of repeated cross-sectional surveys conducted in 2005, 2008, and 2011. Participants were randomly selected from Los Angeles County residents who received WIC services during those years. Results. Consistent with the WIC population in Los Angeles, participants were mostly Latina and had low levels of income and education; more than half were foreign-born. We found small but significant increases from pre- to postimplementation of the new WIC food package in prevalence of prenatal intention to breastfeed and breastfeeding initiation, but no changes in any breastfeeding at 3 and 6 months. The prevalence of exclusive breastfeeding at 3 and 6 months roughly doubled, an increase that remained large and significant after adjustment for other factors. Conclusions. The new food package can improve breastfeeding outcomes in a population at high risk for negative breastfeeding outcomes. Breastfeeding has long been recognized as the best source of infant nutrition, 1,2 with clear benefits to both mothers and children. 3 The American Academy of Pediatrics recommends that infants be exclusively breastfed for the first 6 months of life and that breastfeeding continue with appropriate complementary foods for at least 1 year or more. 2 Despite improvements over the past several decades, 4,5 relatively few mothers and children in the United States meet breastfeeding recommendations. Data from the 2009 National Immunization Survey suggest that just 16% of US children are exclusively breastfed for 6 months and fewer than 26% do any breastfeeding at 1 year. 6 Breastfeeding outcomes vary between populations partially as a result of social and cultural norms, economics, and institutional policies and practices. 7–12 For example, data from the 2007 National Immunization Survey indicate that breastfeeding initiation, duration, and exclusivity rates are comparable between Latinas and Whites, but much lower among Blacks. 6 Breastfeeding rates also vary on the basis of participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). 13 Data from the 2007 National Immunization Survey suggest that just 9.2% of WIC participants exclusively breastfeed for 6 months, compared with 19.2% of eligible nonparticipants. 6 Similarly, only 17.5% of WIC participants were still breastfeeding at 1 year, compared with 30.7% of eligible nonparticipants. 6 As noted by several authors, however, this gap in breastfeeding outcomes is not because participating in WIC negatively affects breastfeeding, but because those who select themselves into the WIC program are among the least likely to breastfeed. 14,15 On October 1, 2009, at the recommendation of an expert panel of the Institute of Medicine, the WIC program implemented changes to the food package provided to mothers and children. 16 A goal of this change was to provide stronger incentives to breastfeed and reduce the amount of formula given to partially breastfed infants. As a result of the new food package, mother–infant dyads who fully breastfeed now receive a food package that includes a greater quantity and larger variety of food than those who partially breastfeed or are fully formula fed. 16 Specifically, infants who are fully breastfed receive double the quantity of infant fruits and vegetables when they are aged 6 to 12 months as those who are partially breastfed or fully formula fed. Fully breastfed infants are also the only group that receives infant meats from ages 6 to 12 months. Fully breastfeeding mothers receive canned fish and increased amounts of milk, cheese, eggs, and fruits and vegetables compared with partially breastfeeding and fully formula-feeding mothers. 16,17 In addition, fully and partially breastfeeding mothers receive food for themselves for as much as 1 year, whereas fully formula-feeding mothers receive food for only 6 months. (For a summary of all WIC food packages changes, please see Cole et al. 16 ) Despite being a clear improvement over its predecessor, questions remain about whether the new food package will substantially improve low breastfeeding rates among WIC participants. 18 Many experts have pointed out that because of the high retail value of formula, the food package for fully formula-feeding dyads may still be more valuable in terms of dollars saved than the package for fully breastfeeding dyads. 18,19 These concerns are at least partially supported by qualitative research among WIC mothers that has found that any free provision of formula is seen as a barrier to breastfeeding. 20,21 Few studies have evaluated changes in breastfeeding rates among WIC participants since the implementation of the new food package. A report commissioned by the US Department of Agriculture (USDA) used several data sources to assess whether breastfeeding rates among participants at 17 local WIC agencies across the country changed after implementation of the new food package. 17 Using administrative data from all mother–infant dyads at the 17 agencies, the study found that breastfeeding initiation rates remained stable after implementation of the new food package. On the basis of a survey of 1617 mothers, the same study found only marginal improvements in breastfeeding intensity among those who received the package in the first 10 weeks of life. 17 Although there were few changes in breastfeeding outcomes, the study found that more mothers enrolled in the package for fully breastfeeding and fully formula-feeding dyads, and fewer enrolled in the package for partially breastfeeding dyads. Other research conducted among WIC mothers in Los Angeles, California, confirmed the finding that package enrollment shifted postimplementation, with more mothers enrolled as fully breastfeeding. 22 The limited research conducted to this point has provided important early insight into some of the effects of the new food package; however, several questions still remain. One important question to consider is whether the improved package offered to fully breastfeeding mother–infant dyads affects breastfeeding outcomes beyond the first 10 weeks. For example, the new package may incentivize women who would otherwise have introduced complementary foods to extend exclusive breastfeeding by a few additional weeks or months, thereby increasing the proportion who reach the recommended 6 months. 2 Another question to consider is whether the impact of the new food package varies across different WIC populations or across local WIC agencies that implement the policy differently. Although the previously mentioned USDA report found no change in breastfeeding intensity among participants nationwide, the proportion of mothers in the Western region who fed their infants exclusively or mostly breast milk during the first 10 weeks of life significantly increased. 22 Although these regional findings are preliminary because of the study’s small sample size, they suggest that further research should evaluate the new food package’s effectiveness in varying geographic, social, and policy contexts. In this study, we use survey data collected from 5020 WIC participants in Los Angeles County during 2005, 2008, and 2011 to assess changes in breastfeeding outcomes that occurred from pre- to postimplementation of the new food package. Consistent with the goals of the new food package, we hypothesized that breastfeeding initiation, duration, and exclusivity would improve among the predominately Latino WIC population in Los Angeles County.
