| Andreyeva and Luedicke, 2013: Federal food package revisions: Effects on purchases of whole-grain products | USDA | Pre-post design using scanner data to assess how the revisions affected purchases of bread and rice among WIC-participating households in Connecticut and Massachusetts | 2,137 WIC-participating households in Connecticut and Massachusetts | 2009 revisions significantly increased purchases of whole grain bread and rice among WIC participating families. |
| Andreyeva and Luedicke, 2014: Incentivizing fruit and vegetable purchases among participants in the Special Supplemental Nutrition Program for Women, Infants, and Children | USDA | Pre-post design using scanner data to examine the impact of the newly implemented CVV on fruit and vegetable purchases | 2,137 WIC-participating households in Connecticut and Massachusetts | Fresh and frozen vegetable purchases increased by 17.5% and 27.8% respectively, and fresh fruit purchases increased by 28.6%. |
| Andreyeva et al., 2011: Changes in access to healthy foods after implementation of the WIC food package revisions | USDA | Evaluate the impact of the WIC food package revisions using multiple determinants of access to healthy food | 252 (all) convenience stores and non-chain grocery stores in 5 towns of Connecticut, including 33 WIC-authorized stores and 219 non-WIC stores | Strong evidence that stores responded to the food package revisions by improving the availability and variety of healthy foods in urban and suburban settings, especially in WIC-authorized stores |
| Andreyeva et al., 2012: Positive influence of the revised Special Supplemental Nutrition Program for Women, Infants, and Children food packages on access to healthy foods | USDA | Pre-post design using a standardized store inventory instrument to evaluate the impact of the revisions using multiple determinants of access to healthy food | 252 (all) convenience stores and nonchain grocery stores in five towns of Connecticut, including 33 WIC-authorized stores and 219 non-WIC stores | Access to healthy foods improved using a composite score measure mostly due to increased availability and variety of whole grain products in urban and suburban settings, especially in WIC-authorized stores. |
| Andreyeva et al., 2013: Effects of reduced juice allowances in food packages for the Women, Infants, and Children Program | USDA | Pre-post design using scanner data to describe changes in purchases of 100% juice and other beverages among WIC participants after the revisions | 2,137 WIC-participating households in Connecticut and Massachusetts | Purchases of 100% juice among WIC households declined by 25%. Little compensation occurred from non-WIC funds for juice or other beverages. |
| Andreyeva et al., 2014: The positive effects of the revised milk and cheese allowances in the Special Supplemental Nutrition Program for Women, Infants, and Children | USDA | Pre-post design using scanner data to examine the effect of the revisions on milk and cheese, and saturated fat intakes | 515 WIC households in Connecticut and Massachusetts | Whole-milk share declined in WIC milk purchases with no change in non-WIC purchases. Total milk volume fell by 14.2%, whole milk by half, and WIC-eligible cheese by 37.2%. Saturated fat from milk and cheese declined by 85 g/month per household in Connecticut and 107 g/month per household in Massachusetts. |
| Gleason and Pooler, 2011: The effects of changes in WIC food packages on redemptions: Final report | USDA | Multimethod, cross-sectional exploratory study to assess participant satisfaction with the revisions by monitoring redemptions before and 6, 12, or 18 months after the 2009 food package changes | WIC participants in Wisconsin: 126,850 prior to the food package change and 116,956 after the food package change | Overall positive response to the food package changes. Decreases were noted in redemptions that differed among racial and ethnic subpopulations. Use of the CVV among racial and ethnic subpopulations were also disproportionate. |
| Herman et al., 2006: Choices made by low-income women provided with an economic supplement for fresh fruit and vegetable purchase | CCRP, CDHS, USDA, NIH, ASNS | Nonequivalent control-group design to investigate whether supplemental financial support specifically for purchase of fresh fruits and vegetables (bimonthly vouchers at the level of $10/wk for 6 months) would result in high uptake of the supplement, and what the individuals would choose to purchase | 602 women enrolled at 3 WIC sites in Los Angeles, California | Wide variety of items purchased at supermarket and farmers' market sites. The 10 most frequently mentioned items: oranges, apples, bananas, peaches, grapes, tomatoes, carrots, lettuce, broccoli, and potatoes. Farmers' market potatoes: 9.1% of total fruit and vegetable items reported. Supermarket potatoes: 10.4% of total fruit and vegetable items reported. |
| IOM, 2011: Planning a WIC research agenda—workshop summary | USDA | Workshop to guide planning for the use of significant WIC research dollars | Considered the WIC target population | Defined research priorities in the areas of birth outcomes, obesity, breastfeeding, food security, nutritional status, and nutrition education, as well as cost, benefits, and effectiveness of the program. |
| Joyce and Reeder, 2015: Changes in breastfeeding among WIC participants following implementation of the new food package | USDA/ERS | Linear regression of national survey data to analyze changes in breastfeeding among WIC participants before and after the new food package | PRAMS in 19 states 2004–2010, PedNSS in 16 states 2007–2010, NIS from 50 states and DC 2004–2010 | Data showed steady upward trends in ever-breastfed infants on WIC but not statistically different from trends in breastfeeding among non-WIC low-income. |
| Kim et al., 2013: Mothers prefer fresh fruits and vegetables over jarred infant fruits and vegetables in the new Special Supplemental Nutrition Program for Women, Infants, and Children food package | USDA | Repeated cross-sectional survey to examine WIC participant use and satisfaction with jarred infant foods, preference for CVVs versus jarred infant foods, and variations among ethnic groups | 2,996 participants who received WIC in California in 2010 and California WIC redemption data | Participants reported high satisfaction with the CVV and jarred infant foods with significant variations across ethnic groups. About two-thirds of participants preferred CVV over jarred infant foods. Redemption rates for jarred foods declined with increasing age of infant across all ethnic groups. |
| Kreider et al., 2016: Identifying the effects of WIC on food insecurity among infants and children | USDA | NHANES analysis to examine the effects of WIC on the nutritional well-being and food security of infants and young children | 4,614 low-income infants and children less than 5 from 1999–2008 NHANES | WIC was estimated to reduce the prevalence of child food insecurity by at least 3.6 percentage points (20%). |
| May et al., 2015: Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) Infant and Toddler Feeding Practices Study 2 (ITFPS-2): Intention to Breastfeed | USDA | Pre-post telephone survey to examine the effects of WIC on attitudes around breastfeeding; comparing data from 1995 to 2013 | A nationally representative sample of 2,649 women either pregnant or having a child under 3 months of age | Overall increase in perceptions of the positive benefits of breastfeeding; overall decrease in the number of women with specific perceived barriers to breastfeeding; increase in number of women reporting that breastfeeding is painful, and no one else can feed the infant. |
| O'Malley et al., 2014: Use of a new availability index to evaluate the effect of policy changes to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) on the food environment in New Orleans | CDC, USDA | Assess changes before and after revisions using a new index developed to monitor the retail environment's adoption of these new food supply requirements (WIC-AI) | 139 and 128 supermarkets, medium and small WIC stores, and non-WIC food stores in New Orleans, LA, were surveyed before and after 2009 package changes, respectively | Median WIC-AI score increased in medium and small stores. In small stores, this increase was mostly attributed to increased availability of cereals and grains, juices and fruit, and infant fruits and vegetables. |
| Ritchie et al., 2014: Satisfaction of California WIC participants with food package changes | USDA | Cross-sectional telephone interviews to assess California WIC participant satisfaction with the revisions, compare based on language preference and timing of WIC enrollment | 2,996 WIC participants in California in 2010 | Most (91.3%) were satisfied with checks for new WIC foods (fruits/vegetables, whole grains, and lower-fat milk), and 82.7% were satisfied with amounts of foods reduced in the new packages in WIC before the revisions. (milk, cheese, eggs, juice). A higher percentage of Spanish speakers than English speakers reported satisfaction. A higher percentage of newer enrollees reported satisfaction compared to those participating |
| Rose et al., 2014: The influence of the WIC food package changes on the retail food environment in New Orleans | CDC, USDA | Pre-post comparison group design with repeat in-store observations to examine the effect of the revisions on the availability of healthy foods in small stores | 102 small stores in New Orleans were visited in 2009 and 91% of these revisited in 2010 (27 WIC and 66 non-WIC) | WIC stores were more likely to improve the availability of lower-fat milks than non-WIC stores and more likely to improve the availability of whole grains. WIC stores showed a relative increase in varieties of fresh fruits and shelf life of vegetables. |
| USDA/FNS, 2011: Evaluation of the birth month breastfeeding changes to the WIC food packages | USDA | Pre-post study to examine changes in breastfeeding initiation, duration, or intensity that occurred following issuance of the 2007 Interim Rule, detailing the food package revisions | 17 randomly sampled local WIC agencies, data collected shortly before and shortly after implementation of the Interim Rule | Notable differences in package assignments were observed, including decreases in the partial breastfeeding package, and increases in the full breastfeeding and full formula packages; infants receiving no formula in the first month increased; the proportion receiving the maximum allowance of formula also increased. No differences were observed in breastfeeding rates or intensity; a slight increase in duration was observed. |
| USDA/FNS, 2012: Effects of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC): A review of recent research | USDA | Comprehensive literature review on WIC program impacts between 2002 and 2010 (published research) and 1999 to 2010 (“gray” literature). Report is intended as an update of the review published by USDA/ERS in 2004 | Peer-reviewed studies focusing on WIC published between 2002 and 2010 or unpublished studies completed between 1999 and 2010 | Prenatal WIC participation is consistently positively associated with gestational age and mean birth weight and negatively associated with incidence of low and very low birth weight when not adjusted for gestational age. There is no clear evidence of an association between WIC and adequate weight gain during pregnancy. |
| USDA/FNS, 2013: WIC food cost report, fiscal year 2010 | USDA | Estimate the average monthly food costs for each WIC participant subgroup and total dollars spent on 17 major categories of WIC-eligible foods in 2010; data are compared to 2005 | National estimates for participation and national average retail prices for each WIC food category were used to generate cost estimates for each food package | The average monthly food cost with rebates in 2010 was $41.44. Costs increased 11% compared to 2005, below the Consumer Price Index for food at home. The relative cost of the infant food package increased. |
| USDA/FNS, 2015: WIC food packages policy options II | USDA | Examine state agency responses to policy options in the Final Rule, determine differences in food options and cost containment measures across state agencies, observe changes in WIC food lists before and after implementation of the revisions | 86 state agencies representing 99.98% of all WIC participants | WIC participants were offered more options after the implementation of the revisions. WIC participants have access to foods consistent with recommendations made by the Dietary Guidelines for Americans and by the American Academy of Pediatrics. State agencies employ a variety of cost containment strategies while increasing options for participants. |
| USDA/FNS, 2016: WIC participant and program characteristics 2014: Food package report | USDA | A supplement to the WIC participant and program characteristics (PC) report, this report provides an overview of the foods prescribed to participants, including a description of the changes in prescription amounts due to the revisions | PC 2014 dataset of participant data submitted by 90 state agencies, approaching 100% of all WIC participants | Between 2008 and 2012, prescriptions of infant formula dropped by 2.3 to 2.4% for younger and middle infants and 4.1% for older infants. |
| Whaley et al., 2012: Revised WIC food package improves diets of WIC families | USDA | Pre-post cross-sectional telephone surveys to explore the impact of the revisions on WIC participant consumption of fruit, vegetables, whole grain food, and lower-fat milk | 3,004 California WIC participants in 2009; 2,996 in 2010 | Whole grain consumption increased by 17.3 percentage points. Whole milk consumption by caregivers and children who usually consumed whole milk decreased by 15.7 and 19.7% respectively. Lower-fat milk consumption increased accordingly. Small but significant increases in consumption of vegetables and fruits were observed. |
| Wilde et al., 2012: Food-package assignments and breastfeeding initiation before and after a change in the Special Supplemental Nutrition Program for Women, Infants, and Children | USDA | Measure changes pre-post WIC package changes in WIC food-package assignments, WIC infant formula amounts, and breastfeeding initiation | National random sample of 17 local WIC agencies. Administrative records for 206,092 dyads with an infant age 0–5 months in the sampled WIC agencies | After the revisions, fewer mothers received the partial breastfeeding package. More mothers received the full breastfeeding package and the full formula package. |
| Zenk et al., 2012: Fruit and vegetable availability and selection: Federal food package revisions, 2009 | USDA, RWJF | Quasi-experimental design with two pre-policy and one post-policy observation to examine availability and selection of commonly consumed and culturally specific vegetables and fruits at authorized WIC vendors before and after the revisions | Data from WIC vendors in 7 northern Illinois counties from 2008 to 2010 (n = 329, 346, and 364 in 2008, 2009, and 2010, respectively) | Availability and selection of overall fresh vegetables and fruits and availability of African-American culturally specific fresh vegetables and fruits improved after the policy change. Modest improvements in overall availability of canned low-sodium vegetables and frozen vegetables and fruits were observed. |
| Zenk et al., 2014: Impact of the revised Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package policy on fruit and vegetable prices | USDA, RWJF, NIH | Quasi-experimental design with two pre-policy and one post-policy observation to observe changes in fruit and vegetable prices pre-post WIC policy changes | Data from WIC vendors in 7 northern Illinois counties from 2008 to 2010 | Revisions contributed to modest reductions in fruit and vegetable prices. WIC participants' purchasing power can differ depending on type of WIC vendor and neighborhood. |
