GAO

United States General Accounting Office

Report to Congressional Committees

March 2001 FOOD ASSISTANCE

Research Provides 

Limited Information 

on the Effectiveness of 

Specific WIC Nutrition 

Services

GAO-01-442

Page 1 GAO-01-442 Research on WIC Nutrition Services

Letter 3

Appendixes Appendix I: Scope and Methodology 20

Appendix II: Research Funding Sources 22

Appendix III: Bibliography of Demonstration Studies 23

Appendix IV: Bibliography of Impact Studies 25

Appendix V: Demonstration Studies: Major Findings, Scope,

and Major Limitations 26

Appendix VI: GAO Contacts and Staff Acknowledgments 28

Table Table 1: Funding for Demonstration and Impact Studies 8

Abbreviations

FNS Department of Agriculture’s Food and Nutrition Service

WIC Special Supplemental Nutrition Program for Woman, Infants and 

Children
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Page 3 GAO-01-442 Research on WIC Nutrition Services

United States General Accounting Office

Washington, D.C. 20548 Letr

March 30, 2001

The Honorable Richard G. Lugar

Chairman

The Honorable Tom Harkin

Ranking Member

Committee on Agriculture, Nutrition, and Forestry

United States Senate

The Honorable John A. Boehner

Chairman

The Honorable George Miller 

Ranking Democratic Member

Committee on Education and the Workforce

House of Representatives

The Special Supplemental Nutrition Program for Women, Infants and 

Children (WIC) is a federally funded nutrition assistance program 

administered by the U.S. Department of Agriculture’s (USDA) Food and 

Nutrition Service (FNS). This program provides supplemental food and 

nutrition services to lower-income pregnant, breastfeeding, and 

postpartum women. The program also serves infants and children up to age 

5 who are at nutritional risk. The WIC program serves a monthly average of 

7.3 million individuals, including about 47 percent of all infants born in the 

United States. In fiscal year 2000, the Congress appropriated $3.9 billion to 

fund WIC, $2.8 billion of which was used to provide food benefits and $1.1 

billion of which was used for nutrition services and program 

administration. The nutrition services part of the program includes 

nutrition education, breastfeeding promotion and support, and referrals to 

health and social services. 

A substantial body of research has examined the overall effectiveness of 

the WIC program, but little is known about what research shows regarding 

the effectiveness of specific WIC nutrition services. This report (1) 

identifies the number and nature of recent studies that have examined the 

effectiveness of three WIC services—nutrition education, breastfeeding 

promotion and support, and referral services—and (2) summarizes what 

the research shows about the effectiveness of these specific nutrition 
Page 4 GAO-01-442 Research on WIC Nutrition Services

services. This report is the fourth in a series providing information on 

various aspects of WIC nutrition services as directed by the William F. 

Goodling Child Nutrition Reauthorization Act of 1998 (P.L. 105-336).1

To identify recent studies that examine the effectiveness of each WIC 

nutrition service, we searched relevant databases, such as the National 

Technical Information Service, Sociological Abstracts, and Wilson Social 

Science Abstracts. We also consulted with USDA WIC program staff and 

other program stakeholders including officials from the National 

Association of WIC Directors. Initially, we identified more than 200 

published WIC studies dealing with various aspects of the WIC program. In 

order to focus on recent research, we eliminated from consideration 

research published prior to 1995. We also eliminated any study that did not 

specifically address the effects of at least one of the three WIC nutrition 

services, whether nutrition education, breastfeeding promotion and 

support, or referral services. We included research that falls in two general 

categories: demonstration studies and impact studies. The demonstration 

studies typically attempt to assess whether special interventions, such as 

hospital visits to promote breastfeeding, more effectively achieve program 

objectives than the usual WIC services. In contrast, impact studies attempt 

to determine whether a WIC nutrition service, such as breastfeeding 

promotion and support, improves WIC participants’ outcomes compared to 

similar individuals who do not participate in the WIC program. 

We conducted our work between May 2000 and March 2001 in accordance 

with generally accepted government auditing standards. Appendix I 

provides a more detailed description of the methodology we used to 

conduct this work.

Results in Brief We identified 19 studies published since 1995 that examine the 

effectiveness of WIC nutrition services. Twelve of the 19 are demonstration 

studies; seven are impact studies. Most of the studies—seven of the 

demonstration studies and four of the impact studies—focused on 

breastfeeding promotion and support. 

1

Food Assistance: Financial Information on WIC Nutrition Services and Administrative 

Costs (GAO/RCED-00-66, Mar. 6, 2000); Food Assistance: Activities and Use of Nonprogram 

Resources at Six WIC Agencies (GAO/RCED-00-202, Sept. 29, 2000); Food Assistance: 

Performance Measures for Assessing Three WIC Services (GAO/01-339, Feb. 28, 2001).
Page 5 GAO-01-442 Research on WIC Nutrition Services

Despite some methodological limitations, the results of the 12 

demonstration studies suggest that certain types of nutrition service 

interventions, such as providing breastfeeding support services in the 

hospital after delivery, have the potential to be more effective than the usual 

WIC interventions. Our analysis of the demonstration studies suggests that 

the more effective strategies may cost more than usual WIC approaches. 

However, only one of the studies specifically addressed the potential costs 

of new interventions. The results of the seven impact studies provide few, if 

any, insights into the effectiveness of specific WIC nutrition services. The 

results of the impact studies are severely limited by methodological 

constraints, including the use of outdated and poor-quality data. 

We are making a recommendation to USDA aimed at improving 

demonstration research by incorporating relevant cost information. We 

provided a draft of this report to USDA for its review and comment. In 

commenting on the draft report, USDA generally agreed with the report 

and its recommendation. The agency provided some technical comments, 

which we incorporated as appropriate.

Background WIC, which began as a 2-year pilot program in 1972 and was authorized as a 

permanent program in 1974, is part of the nutrition safety net available to 

low-income women and their children. FNS provides annual cash grants for 

food benefits and nutrition services to fund program operations at 88 statelevel WIC agencies (including agencies in all 50 states, the District of 

Columbia, American Samoa, the Commonwealth of Puerto Rico, Guam, the 

U.S. Virgin Islands, and 33 Indian Tribal Organizations). Some of these 

state-level agencies—those that operate the program at both the state and 

local levels—retain all of their federal WIC grants. Most state-level 

agencies, however, retain a portion of their grants and pass the remaining 

funds to over 1,800 local WIC agencies. 

In fiscal year 2000, about $2.8 billion in federal program funds were used to 

provide food benefits to participants. Typically food benefits are in the 

form of vouchers or checks that participants can use to obtain approved 

foods at authorized retail food stores. An additional $1.1 billion in federal 

funds were used for nutrition services and program administration. 

Program administration includes, among other things, activities related to 

accounting and record keeping, outreach, monitoring and financial audits, 

and general management. Nutrition services include activities related to 

determining participants’ eligibility and issuing food benefits, as well as the 

following:
Page 6 GAO-01-442 Research on WIC Nutrition Services

• Nutrition education: WIC offers classes, counseling, and other activities 

to teach participants about proper nutrition, positive food habits, and 

the prevention of nutrition-related problems. 

• Breastfeeding promotion and support: To promote breastfeeding, WIC 

offers individual and group counseling sessions at WIC clinics or the 

hospital. Breastfeeding support can include telephone or in-person 

consultation with breastfeeding mothers.

• Referral to health care and social services: WIC agencies provide 

participants with information on health care and social services and 

refer them to providers including immunization clinics and the Food 

Stamp and Medicaid programs. 

By law, spending for nutrition education and breastfeeding promotion and 

support activities combined must equal at least one-sixth of a state’s total 

annual expenditures for nutrition services and administration plus a target 

amount for breastfeeding promotion and support that is established by FNS 

at the beginning of each fiscal year.2

 There is no minimum spending 

requirement for referral activities. 

Over the past 20 years, government agencies such as USDA,3

 the Centers 

for Disease Control and Prevention, and GAO,4 as well as universities and 

private research organizations, have conducted a substantial body of 

research on the effects of the entire WIC program. Some of the 

accumulated body of WIC research and evaluations provides nationwide 

assessments of WIC’s effects. Most of it has focused on the effect of 

program participation on birth outcomes and the nutritional status of 

program participants. USDA has a review under way describing and 

assessing research on the diet and health outcomes of its nutrition 

programs, including WIC. The results of this review, set for release later 

2

In fiscal year 2000, the state agencies’ targets for breastfeeding promotion and support 

were determined by multiplying $23.92 by the average number of pregnant and 

breastfeeding participants during the last 3 months for which there were final data (MayJune 1999). 

3

In 1998, the Agriculture, Rural Development, Food and Drug Administration, and Related 

Agencies Appropriations Act of 1998 (P.L. 105-86) effectively transferred primary 

responsibility for research funding on food assistance and nutrition programs—including 

WIC—from FNS to USDA’s Economic Research Service. Previously, USDA had spent about 

$3.5 million annually on such WIC research.

4

Breastfeeding: WIC’s Efforts to Promote Breastfeeding Have Increased (GAO/HRD-94-13, 

Dec. 6, 1993);Early Intervention: Federal Investments Like WIC Can Produce Savings

(GAO/HRD-92-18, Apr. 7, 1992)
Page 7 GAO-01-442 Research on WIC Nutrition Services

this year, will provide detailed information on over 70 studies, most of 

which examine WIC’s effects on birth outcomes or on the nutrition status 

of participants. While the USDA review will not focus on the impacts of 

specific nutrition services, it will include studies that examined the WIC 

program’s effects on the initiation and duration of breastfeeding and the 

immunization status of children. These two health-related outcomes are 

directly linked to two of the three nutrition services addressed in this 

report—breastfeeding promotion and support and referral services. 

However, because the USDA review is generally focused on overall 

program impacts, its report probably will not include descriptions or 

assessments of many of the demonstration studies included in this report. 

Most of the Recent 

Research Evaluates 

Demonstrations of 

Special Interventions 

The 19 studies we identified included almost twice as many demonstration 

studies as impact studies. Of the 12 demonstration studies, 3 look at special 

interventions in nutrition education, 6 look at special interventions in 

breastfeeding promotion and support, and 3 look at special interventions in 

referral to health and social services. Of the seven impact studies, one 

examines nutrition education, four assess breastfeeding promotion and 

support services, and two evaluate WIC health referrals.5

Most of the studies have a relatively limited geographic scope. Among the 

12 demonstration studies, 11 are at the substate level. They generally study 

multiple WIC sites and/or multiple counties, but without sufficient 

sampling rigor to draw valid statewide conclusions. The results of one 

demonstration study are generalized to an entire state. Among the seven 

impact studies, three are at the substate level, one is statewide, and three 

are national in scope. 

The 19 studies received funding from various sources. Table 1 provides 

details on project funding for the 12 demonstration studies and 7 impact 

studies.

5

One impact study—Fox and others—is primarily a nutrition education evaluation, so we 

count it as such. However, it also contains information on WIC breastfeeding programs and 

their effects on initiation and duration.
Page 8 GAO-01-442 Research on WIC Nutrition Services

Table 1: Funding for Demonstration and Impact Studies 

a

These columns do not sum to 12 and 7, respectively, because some studies received funding from 

multiple sources. 

Appendix II provides detailed information on the funding sources for the 19 

studies reviewed for this report.

Special Interventions 

Improve Participant 

Outcomes but 

Research Says Little 

About the 

Effectiveness of 

Individual Nutrition 

Services

While all 19 studies suffer from methodological limitations, those 

limitations have varying consequences. Despite their limitations, the results 

of the 12 demonstration studies suggest that special interventions have 

some potential to improve nutrition service effectiveness over WIC 

interventions typically used; though, based on our analysis of these studies, 

it appears that additional resources may have to be committed to achieve 

this added effectiveness. However, the methodological limitations of the 

seven impact studies enable them to provide only very limited information 

on the effects of any one nutrition service. Appendixes III and IV contain 

lists of the demonstration and impact studies, respectively, reviewed for 

this report.

Demonstration Studies 

Indicate Some Special 

Interventions Improve 

Participant Outcomes 

The 12 demonstration studies evaluate a range of different special 

interventions. To varying degrees, all were more effective than usual WIC 

interventions. Examples of the special interventions include the following:

• Breastfeeding promotion and support. Gross and others evaluated 

special interventions designed to encourage breastfeeding among 

African-American WIC participants.6

 Mothers in the three special 

Source of funding

Number of

demonstration

studies fundeda

Number of impact

studies fundeda

USDA 1 2

U.S. Department of Health and Human 

Services

1 0

Centers for Disease Control and 

Prevention

5 0

State departments of health 4 1

Universities and research institutes 1 2

Private organizations 1 1

Unspecified 1 3
Page 9 GAO-01-442 Research on WIC Nutrition Services

intervention groups were provided a motivational video or peer 

counseling or a combination of the video and counseling. Mothers in the 

control group received the standard WIC service that incorporated 

encouragement and support to breastfeed and brochures about 

breastfeeding during discussions about infant feeding. Mothers in the 

special intervention groups were twice as likely as mothers receiving 

the standard WIC infant feeding education to be breastfeeding 8 weeks 

and 16 weeks after giving birth, even accounting for factors that could 

increase breastfeeding duration, such as prior breastfeeding experience.

• Health referrals. Birkhead and others evaluated two special 

interventions designed to increase the number of WIC-eligible children 

who receive measles immunizations.7

 The special interventions included 

having WIC staff escort children to an on-site immunization clinic and a 

food voucher incentive in which WIC staff provided only a 1-month 

supply of vouchers to parents, rather than the usual 2-month supply, 

until the parents provided documentation that their children’s 

immunizations were up-to-date. The standard WIC immunization 

referral consisted of notifying parents that immunizations were due, 

providing information on the benefits of immunizations, and providing 

the names and telephone numbers of local health facilities that 

immunize children. Children at escort sites were about five times more 

likely to be immunized than children at standard referral sites; children 

at voucher incentive sites were about three times more likely to receive 

immunizations. 

• Nutrition education. Havas and others evaluated a special intervention 

designed to increase WIC participants’ consumption of fruits and 

vegetables.8

 The special intervention—Maryland’s “5-A-Day” program—

was a series of three 45-minute group sessions taught by former WIC 

participants, or “peer educators,” that incorporated special visual 

materials and included direct mailings to participants. The standard 

6

Susan M. Gross, Laura E. Caulfield, Margaret E. Bentley, and others, “Counseling and 

Motivational Videotapes Increase Duration of Breastfeeding in African-American WIC 

Participants Who Initiate Breastfeeding,” Journal of the American Dietetic Association, Vol. 

98, No. 2 (1998), p. 143.

7

Guthrie S. Birkhead, Charles W. LeBaron, Patricia Parsons, and others, “The Immunization 

of Children Enrolled in the Special Supplemental Food Program for Women, Infants, and 

Children (WIC),” Journal of the American Medical Association, Vol. 274, No. 4 (1995), p. 312.

8

Steven Havas, Jean Anliker, Dorothy Damron, and others, “Final Results of the Maryland 

WIC 5-A-Day Promotion Program,” American Journal of Public Health, Vol. 88, No. 8 (1998), 

p. 1161.
Page 10 GAO-01-442 Research on WIC Nutrition Services

service generally included less than 10 minutes of nutrition education 

conversation between WIC staff and participants when they picked up 

their food voucher every other month. Compared to participants 

receiving the standard WIC nutrition education program, participants 

exposed to the special intervention displayed a significant increase in 

nutrition knowledge and in the consumption of fruits and vegetables. 

Each of the demonstration studies we reviewed suffers from 

methodological limitations that, while not invalidating the study’s findings, 

should be taken into account. The limitations we identified are common in 

studies that attempt to assess the extent to which social or health program 

interventions—not other factors—are responsible for changes in program 

participants’ behaviors or health. The major methodological limitations of 

the demonstration studies we reviewed include the following:

• Lack of control group. To help isolate the effects of an intervention, an 

evaluation study must compare people receiving the special 

intervention to similar people receiving standard WIC services. The 

difference between these groups can provide insight into whether the 

special intervention is more effective than standard WIC practice. Not 

having such a comparison obscures the relationship between the 

intervention and participant outcomes. Four of the studies we reviewed 

had a weak research design associated with a lack of control group. For 

example, Hoekstra and others attempted to evaluate the effectiveness of 

a new voucher incentive program in increasing WIC children’s rates of 

immunization.9

 However, the researchers did not compare the group 

receiving the special intervention to a group receiving standard services. 

Instead, they compared three special intervention groups to themselves 

at different points in time over a period of 14 months. Without a control 

group that does not participate in the voucher intervention, it is difficult 

to attribute any changes the researchers noticed to the special 

intervention. 

• Inappropriate data analysis techniques. The analytic techniques used in 

a study must suit the available data and the research design—in 

particular, they should be selected for their ability to help isolate the 

effects of the intervention. Three of the demonstration studies we 

9

Edward J. Hoekstra, Charles W. LeBaron, Yannis Megaloeconomou, and others, “Impact of 

a Large-Scale Immunization Initiative in the Special Supplemental Nutrition Program for 

Women, Infants, and Children (WIC),” Journal of the American Medical Association, Vol. 

280, No. 13 (1998), p. 1143.
Page 11 GAO-01-442 Research on WIC Nutrition Services

reviewed used questionable analytic techniques. For example, Havas 

and others found that a special peer counselor program was effective in 

increasing nutrition knowledge and the consumption of fruits and 

vegetables. To reach this finding, Havas and others compared the 

average fruit and vegetable consumption of the special “5-a-Day” group 

to the average fruit and vegetable consumption of a group exposed to 

the standard WIC nutrition education. The comparison, which examined 

the linkage between demographic characteristics, such as race, and fruit 

and vegetable consumption, did not take into account the simultaneous 

influence of other characteristics, such as education level, on 

consumption. Without an analysis technique, such as multiple 

regression, that can account for the influence of several factors at once, 

determining the extent to which the observed differences in fruit and 

vegetable consumption are the result of the “5-A-Day” program is greatly 

complicated.

• Selection bias. Ideally, study participants should be randomly assigned 

to intervention and control groups to ensure that all participant 

characteristics will, on average, be the same from one group to another. 

A selection bias exists if the two groups differ in some systematic way. 

Selection bias makes it more difficult to attribute an observed difference 

in outcomes between the two groups to any one factor, such as the 

intervention. Six of the demonstration studies we reviewed have a 

possible selection bias. For example, Tuttle and Dewey examined the 

influence of a new, culturally sensitive breastfeeding education 

intervention on the initiation and duration of breastfeeding among 

Hmong WIC participants in Northern California.10, 11 However, the 

study’s research design depended on women to volunteer to participate 

in the study—the women self-selected themselves to participate in the 

special intervention. Thus, those choosing to participate in the special 

intervention may have shared characteristics (for example, an already 

existing inclination to breastfeed) that did not exist in those women 

who chose not to participate. If present, selection bias could lead the 

researcher to overstate the benefits of the special intervention. 

• Low response rate/missing data. To substantially reduce data reliability 

concerns, experts agree that under most circumstances researchers 

need at least 75 percent of the people they ask to participate in a study 

10Cynthia Reeves Tuttle and Kathryn G. Dewey, “Impact of a Breastfeeding Promotion 

Program for Hmong Women at Selected WIC Sites in Northern California,” Journal of 

Nutrition Education, Vol. 27, No. 2 (1995), p. 69.

11Most Hmong living in the United States today came from Laos. 
Page 12 GAO-01-442 Research on WIC Nutrition Services

to agree. Excessive missing data, or poor response rates, may skew 

research findings. Missing data or poor response rate was a limitation in 

five of the demonstration studies. For example, Ahluwalia and others 

evaluated five new breastfeeding interventions, and attributed 

significant improvements in breastfeeding initiation to them.12 However, 

the database employed by the study contained breastfeeding initiation 

data for only 52 percent of the women in the sample. 

• Measurement error. For an analysis to produce reliable results, the 

measures in the analysis must be accurate. Measurement error is the 

difference between a measured value and its true value. Five of the 

studies have potential measurement errors. For example, Shaw and 

Kaczorowski sought to examine the effectiveness of a peer counseling 

program on breastfeeding initiation and duration by asking new mothers 

to recall interactions with breastfeeding peer counselors that took place 

at the time of birth.13 Mothers were interviewed 6 weeks to 6 months 

after giving birth. If memory lapses occurred, new mothers may have 

incorrectly recalled their dealings with peer counselors, thereby 

potentially introducing measurement error into the data. 

Appendix V shows the major findings and methodological limitations of 

each of the 12 demonstration studies.

Our analysis suggests that the effective interventions described in the 

demonstration studies may cost more than standard WIC approaches. For 

example, most breastfeeding special interventions were specifically 

designed to increase the amount of counseling and support provided to 

prenatal and postpartum women. Although only one of the demonstration 

studies provided information about the additional costs associated with 

such interventions, it is reasonable to expect that such one-on-one support 

will cost more than the standard WIC program.

Two of the demonstration studies help to illustrate the linkage between 

resource commitment and results achieved. The first, Ahluwalia and 

others, which found that a hospital-based strategy providing bedside 

12Indu B. Ahluwalia, Irene Tessaro, Laurence M. Grummer-Strawn, and others, “Georgia’s 

Breastfeeding Promotion Program for Low-Income Women,” Pediatrics, Vol. 105, No. 6 

(2000), p. 85.

13Elizabeth Shaw and Janusz Kaczorowski, “The Effect of a Peer Counseling Program on 

Breastfeeding Initiation and Longevity in a Low-Income Rural Population,” Journal of 

Human Lactation, Vol. 15, No. 1 (1999), p. 19.
Page 13 GAO-01-442 Research on WIC Nutrition Services

support and counseling to women who had just given birth, was the most 

effective at increasing breastfeeding initiation rates out of five new 

strategies evaluated. This strategy clearly required more resources than the 

standard practice of providing counseling and brochures to participants 

during a visit to the WIC clinic. The second study, Weimer, which was 

funded by USDA, focused on a special intervention that was similarly 

resource-intensive. It reported that providing one-on-one support in the 

hospital after delivery, followed by an in-home visit within 72 hours of 

birth, increased breastfeeding duration. However, neither study provided 

any information about the additional costs needed to implement these 

special interventions. 

Only one of the 12 demonstration studies we reviewed, Hutchins and 

others, provided any information about the costs associated with the 

implementation of the special intervention.14 This study reported that 

vaccinations increased at sites providing vaccination screening and 

voucher incentives (until their children are immunized, a family must visit 

the clinic monthly—rather than every 3 months—to pick up WIC 

vouchers). This study uses what its authors term “crude” cost-effectiveness 

ratios to estimate the average cost for each additional child with up-to-date 

immunizations. These costs range between $30 and $73, depending on the 

number of enrolled children and rates of active participation. 

Impact Research Provides 

Very Limited Information on 

the Effectiveness of WIC’s 

Individual Nutrition 

Services

The seven impact research studies we reviewed provide few conclusive 

insights into the recent effectiveness of WIC breastfeeding promotion and 

support, referral services, or nutrition education services. 

14Sonja S. Hutchins, Jorge Rosenthal, Pamela Eason, and others, “Effectiveness and CostEffectiveness of Linking the Special Supplemental Program for Women, Infants, and 

Children (WIC) and Immunization Activities,” Journal of Public Health Policy, Vol. 20, No. 4 

(1999), p. 408.
Page 14 GAO-01-442 Research on WIC Nutrition Services

Breastfeeding Promotion 

and Support

Three of the four impact studies that focused on breastfeeding promotion 

and support—Schwartz and others,15 Balcazar and others,16 and Timbo and 

others17—use old data from the 1988 National Maternal and Infant Health 

Survey. Although, according to FNS officials, this survey represents the 

most recent data available, much has changed in the program since 1988, 

including the characteristics of WIC participants and the emphasis the 

program places on breastfeeding. As a result, these studies’ findings shed 

little light on the program’s current effects. Although the fourth study, 

Wiemann and others,18 uses data from the mid-1990s, its limited scope, in 

terms of geography and participants, constrains the applicability of its 

findings. This study, with data collected from 684 adolescent mothers who 

gave birth at a hospital in Galveston, Texas, could have some specialized 

usefulness, but would have to be replicated at many other sites to provide 

insights into the broader effectiveness of WIC’s breastfeeding promotion 

and support services. In addition, since adolescent mothers comprise only 

about 11 percent of all WIC mothers, the study’s focus on them further 

compromises its more general usefulness.19

Taken as whole, the inconsistency in the findings of these four studies 

further limit their usefulness in assessing the effects of WIC’s breastfeeding 

promotion and support program. For example, Wiemann and others and 

Balcazar and others find that WIC enrollment is a significant factor in some 

mothers’ decision to bottle-feed, while Timbo and others, and Schwartz and 

15J. Brad Schwartz, Barry M. Popkin, Janet Tognetti, and others, “Does WIC Participation 

Improve Breastfeeding Practices,” American Journal of Public Health, Vol. 85, No. 5 (1995), 

p. 729.

16Hector Balcazar, Catherine M. Trier, and Jose A. Cobas, “What Predicts Breastfeeding 

Intention in Mexican-American and Non-Hispanic White Women? Evidence from a National 

Survey,” Birth, Vol. 22, No. 2 (1995), p. 74.

17Babgaleh Timbo, Sean Altekruse, Marcia Headrick, and others, “Breastfeeding Among 

Black Mothers: Evidence Supporting the Need for Prenatal Intervention,” Journal of the 

Society of Pediatric Nurses, Vol. 1, No. 1 (1996), p. 35.

18Constance M. Wiemann, Jacqueline C. DuBois, and Abbey B. Berenson, “Racial/Ethnic 

Differences in the Decision to Breastfeed Among Adolescent Mothers,” Pediatrics, Vol. 101, 

No. 6 (1998), p. 11.

19Susan Barlett, Melanie Brown-Lyons, Douglas Moore, and others, WIC Participant and 

Program Characteristics 1998 (Alexandria, Va.: USDA, Food and Nutrition Service, 2000), p. 

38.
Page 15 GAO-01-442 Research on WIC Nutrition Services

others, conclude that WIC participation increases breastfeeding. No 

consistent message emerges from the studies.

Referral Services The two referral service impact studies have methodological constraints 

that, to varying degrees, limit their usefulness in assessing the effectiveness 

of WIC referral services. The first study, Suarez and others, using survey 

data from 30 counties in Texas, found that children who are enrolled in 

WIC are significantly more likely than children who are not enrolled to be 

up-to-date on their immunizations, regardless of other intervening factors 

such as the child’s age, ethnicity, or the family’s income.20 Although this 

study likely contains some measurement error, it provides at least limited 

evidence that WIC referral services are effective in increasing 

immunization rates.21 In contrast, due to major methodological problems, 

the second referral study, McCunniff and others,22 provides little useful 

information on the effectiveness of WIC referral services. This study is 

based on self-administered questionnaire data collected from a sample of 

mothers at three WIC sites in Kansas City, Missouri. The study found that 

when taking into account factors such as WIC referral, child’s age, 

household size, and availability of dental insurance, only the age of the 

child had a significant, independent effect on the likelihood that children 

will visit a dentist. There are two principal limitations to this study. First, 

almost 40 percent of the sampled children were younger than 1 year old. 

Because many children less than 1 year of age do not yet have teeth, they 

are much less likely to have made a dental visit, thus reducing the study’s 

ability to identify factors associated with dental visits other than age. The 

second major limitation is the measurement error associated with the 

reliance on self-reported questionnaire data about visits to the dentist. The 

study did not attempt to verify questionnaire responses through a review of 

dental records. The authors suggested that such reviews would have 

increased the accuracy of the self-reported data. As a result of these 

serious methodological problems, it is likely that McCunniff and others has 

20Lucina Suarez, Diane M. Simpson, and David R. Smith, “The Impact of Public Assistance 

Factors on the Immunization Levels of Children Younger Than 2 Years,” American Journal of 

Public Health, Vol. 87, No. 5 (1997), p. 845.

21Measurement error is likely in Suarez and others because the immunization information 

provided by 28 percent of those interviewed was based on parents’ recollections of their 

children’s immunizations, rather than medical records or other documentation.

22Michael D. McCunniff, Peter C. Damiano, Michael J. Kanellis, and others, “The Impact of 

WIC Dental Screenings and Referrals on Utilization of Dental Services Among Low-Income 

Children,” Pediatric Dentistry, Vol. 20, No. 3 (1998), p. 181.
Page 16 GAO-01-442 Research on WIC Nutrition Services

only limited relevance to understanding the effectiveness of WIC referral 

services.

Nutrition Education The one study that primarily focused on the impact of nutrition education, 

Fox and others, also examined breastfeeding programs and their 

effectiveness.23 However, Fox and others was limited geographically, and 

had other limitations that reduce its usefulness in assessing the 

effectiveness of WIC’s nutrition education. For example, its scope was 

limited in that it focused on pregnant and postpartum women at six WIC 

sites, in three states. Within this limited context, the study describes 

program and participant characteristics; the nutrition services offered 

(including breastfeeding promotion and support); participants’ receipt of 

and satisfaction with these services; and changes in participants’

knowledge and behaviors between the time of prenatal WIC certification 

and 4 to 6 months postpartum. The study also attempted to assess the 

impact of WIC nutrition education on participants’ knowledge and 

behavior. Although the study concluded that participants’ nutrition 

knowledge and behavior improved significantly over the course of the 

study, attributing these changes to WIC is problematic because the study 

did not use a control group. Instead, Fox and others compared intervention 

groups at different points in time. The study also concluded that (1) WIC 

participation did not significantly increase breastfeeding initiation or 

duration; and (2) women’s decisions regarding infant feeding are strongly 

associated with intentions formed during pregnancy.

Conclusion Demonstration studies, despite some methodological limitations, provide 

program managers and policymakers with some useful information about 

the types of WIC nutrition service interventions that can have positive 

impacts on participants. However, only one recent demonstration study 

provides any information on the costs associated with implementing 

various interventions. Given the limited resources available to provide WIC 

nutrition services, information about the costs to provide effective services 

could play a critical role in managers’ decisions to implement the 

intervention and policymakers’ decisions about funding the intervention. 

23Mary Kay Fox, Nancy Burstein, Jenny Golay, and others, WIC Nutrition Education 

Assessment Study: Final Report (Alexandria, Va.: U.S. Department of Agriculture, Food and 

Nutrition Service, 1999), p. vii.
Page 17 GAO-01-442 Research on WIC Nutrition Services

Recommendation In order to maximize the value of nutrition education, breastfeeding 

promotion and support, and referral service demonstration and evaluation 

research funded by USDA, we recommend that the Secretary of Agriculture 

direct officials responsible for implementing such research to require that 

this research include an assessment of the costs associated with the special 

intervention being evaluated.

Agency Comments and 

Our Response

We provided a draft of this report to the Department of Agriculture’s Food 

and Nutrition Service for review and comment. We met with Food and 

Nutrition Service officials, including the Acting Associate Deputy 

Administrator for Special Nutrition Programs. The agency officials 

generally agreed with the report’s findings and recommendation. However, 

the officials questioned why our recommendation did not address actions 

that WIC researchers should take to deal with some of the methodological 

limitations we identified in research evaluating the effectiveness of WIC 

services. We believe that USDA has a responsibility to ensure that the WIC 

and other nutrition program research it funds are of high quality. However, 

our review was not designed to examine USDA’s policies and procedures to 

ensure the quality of the research it funds or the practices it employs to 

promote high-quality research in studies it does not fund. As a result, we 

are not making any specific recommendations concerning how USDA 

might improve the quality of WIC research at this time.

The officials also provided some technical changes and clarifications to the 

report, which we incorporated as appropriate. 

We are sending copies of this report to the appropriate congressional 

committees; interested Members of the Congress; the Honorable Ann M. 

Veneman, Secretary of Agriculture; the Honorable Mitchell E. Daniels, Jr., 

Director of the Office of Management and Budget; and other interested 

parties. We will also make copies available upon request.
Page 18 GAO-01-442 Research on WIC Nutrition Services

If you or your staff have any questions about this report, please contact me 

or Thomas E. Slomba at (202) 512-7215. Key contributors to this report are 

listed in appendix VI.

Robert E. Robertson

Director, Employment, Workforce, and 

 Income Security Issues
Page 19 GAO-01-442 Research on WIC Nutrition Services
Page 20 GAO-01-442 Research on WIC Nutrition Services

Appendix I

Scope and Methodology ApApenednxidexiIs

To identify recent studies that examine the effectiveness of the Special 

Supplemental Nutrition Program for Women, Infants and Children (WIC) 

nutrition education, breastfeeding promotion and support, and referral 

services, we searched relevant databases, such as National Technical 

Information Service, Sociological Abstracts, and Wilson Social Science 

Abstracts. We also consulted with the U.S. Department of Agriculture 

(USDA) WIC program staff and other program stakeholders, including 

officials from the National Association of WIC Directors. Through this 

process, we identified 209 items published from 1988 through 2000 dealing 

with various aspects of the WIC program. To be used in our review, 

individual items had to meet each of the following criteria: 

• publication in a refereed medium (for example, a journal article, book or 

book chapter, USDA-issued report); 

• publication date of 1995 or later; 

• examination of one or more of WIC’s nutrition services (breastfeeding 

promotion and support, nutrition education, or health referrals); and 

• original analysis of a specific nutrition service’s effectiveness.

Altogether, only 19 items met all four criteria. Many—86 of the 190 items 

we rejected—were published prior to 1995, and therefore do not satisfy our 

definition of recent studies. (We established 1995 as the cutoff to enable us 

to better examine the program as it currently operates.) We eliminated the 

remaining 104 items because they did not meet one or more of our criteria. 

For example, some items appeared in our literature search as professional 

papers delivered at conferences; thus, they did not undergo any formal 

referee process. Other items were published as reviews or summaries of 

original research, but did not include any original research of their own. 

Some items do not focus on the effectiveness of specific WIC nutrition 

services. For example, one study examines the general effects of food 

programs—including WIC and other food assistance programs such as food 

stamps—on diet, but does not evaluate the effectiveness of specific WIC 

nutrition service programs.

Once we narrowed the scope of our study, we met with staff in the USDA’s 

Food and Nutrition Service Office of Analysis, Nutrition and Evaluation to 

ensure that our methodology did not exclude any important studies. 

According to these officials, our approach successfully identified all of the 

major recent evaluation studies on WIC nutrition services. 

We then conducted detailed reviews of the 19 studies. These reviews 

entailed an evaluation of each study’s research methodology, including its 
Appendix I

Scope and Methodology

Page 21 GAO-01-442 Research on WIC Nutrition Services

data quality, research design, and analytic techniques, as well as a summary 

of its major findings and conclusions. We also assessed the extent to which 

each study’s data and methods support its findings and conclusions.
Page 22 GAO-01-442 Research on WIC Nutrition Services

Appendix II

Research Funding Sources ApendxiI

Study Funding source(s)

Demonstration studies

Ahluwalia and others, 2000 Centers for Disease Control and Prevention

Hutchins and others, 1999 Centers for Disease Control and Prevention

Shaw and Kaczorowski, 1999 Unspecified

Abusabha and others, 1998 New Mexico Department of Health

Gross and others, 1998 U.S. Department of Health and Human Services

Havas and others, 1998 National Cancer Institute; Maryland Department of 

Health and Mental Hygiene

Hoekstra and others, 1998 Centers for Disease Control and Prevention

Weimer, 1998 USDA/ERS

Grummer-Strawn and others, 1997 Centers for Disease Control and Prevention

Reifsnider and Eckhart, 1997 Beta Delta Chapter at Large; Sigma Theta Tau

Birkhead and others, 1995 Centers for Disease Control and Prevention

Tuttle and Dewey, 1995 California State Department of Health

Impact studies

Fox and others, 1999 USDA/FNS

McCunniff and others, 1998 Unspecified

Wiemann and others, 1998 National Institute on Drug Abuse;

Hogg Foundation for Mental Health

Suarez and others, 1997 Texas Department of Health; Public Policy 

Research Institute, Texas A&M University

Timbo and others, 1996 Unspecified

Balcazar and others, 1995 Unspecified

Schwartz and others, 1995 USDA/FNS; Research Triangle Institute, University 

of North Carolina
Page 23 GAO-01-442 Research on WIC Nutrition Services

Appendix III

Bibliography of Demonstration Studies ApendxiI

Breastfeeding 

Promotion and Support

Ahluwalia, Indu B., Irene Tessaro, Laurence M. Grummer-Strawn, and 

others. “Georgia’s Breastfeeding Promotion Program for Low-Income 

Women.” Pediatrics, Vol. 105, No. 6 (2000), pp. 85–91.

Shaw, Elizabeth, and Janusz Kaczorowski. “The Effect of a Peer Counseling 

Program on Breastfeeding Initiation and Longevity in a Low-Income Rural 

Population.” Journal of Human Lactation, Vol. 15, No. 1 (1999), pp. 19–25.

Gross, Susan M., Laura E. Caulfield, Margaret E. Bentley, and others. 

“Counseling and Motivational Videotapes Increase Duration of BreastFeeding in African-American WIC Participants Who Initiate BreastFeeding.” Journal of the American Dietetic Association, Vol. 98, No. 2 

(1998), pp. 143–148.

Weimer, Jon P. Breastfeeding Promotion Research: The ES/WIC Nutrition 

Education Initiative and Economic Considerations. Washington, D.C.: U.S. 

Department of Agriculture, Economic Research Service, 1998.

Grummer-Strawn, Laurence M., Susan P. Rice, Kathy Dugas, and others. “An 

Evaluation of Breastfeeding Promotion Through Peer Counseling in 

Mississippi WIC Clinics.” Maternal and Child Health Journal, Vol. 1, No. 1 

(1997), pp. 35–42.

Reifsnider, Elizabeth, and Donna Eckhart. “Prenatal Breastfeeding 

Education: Its Effect on Breastfeeding Among WIC Participants.” Journal 

of Human Lactation, Vol. 13, No. 2 (1997), pp. 121–125.

Tuttle, Cynthia Reeves, and Kathryn G. Dewey. “Impact of a Breastfeeding 

Promotion Program for Hmong Women at Selected WIC Sites in Northern 

California.” Journal of Nutrition Education, Vol. 27, No. 2 (1995), pp. 69–74.

Nutrition Education Abusabha, Rayane, Cheryl Achterberg, and Jeannie McKenzie. “Evaluation 

of Nutrition Education in WIC.” Journal of Family and Consumer Sciences, 

Winter (1998), pp. 98–104.

Havas, Stephen, Jean Anliker, Dorothy Damron, and others. “Final Results 

of the Maryland WIC 5-A-Day Promotion Program.” American Journal of 

Public Health, Vol. 88, No. 8 (1998), pp. 1161–1167.
Appendix III

Bibliography of Demonstration Studies

Page 24 GAO-01-442 Research on WIC Nutrition Services

Referrals Hutchins, Sonja S., Jorge Rosenthal, Pamela Eason, and others. 

“Effectiveness and Cost-Effectiveness of Linking the Special Supplemental 

Program for Women, Infants, and Children (WIC) and Immunization 

Activities.” Journal of Public Health Policy, Vol. 20, No. 4 (1999), pp. 408–

426.

Hoekstra, Edward J., Charles W. LeBaron, Yannis Megaloeconomou, and 

others. “Impact of a Large-Scale Immunization Initiative in the Special 

Supplemental Nutrition Program for Women, Infants, and Children (WIC).”

Journal of the American Medical Association, Vol. 280, No. 13 (1998), pp. 

1143–1147.

Birkhead, Guthrie S., Charles W. LeBaron, Patricia Parsons, and others. 

“The Immunization of Children Enrolled in the Special Supplemental Food 

Program for Women, Infants, and Children (WIC).” Journal of the American 

Medical Association, Vol. 274, No. 4 (1995), pp. 312–316.
Page 25 GAO-01-442 Research on WIC Nutrition Services

Appendix IV

Bibliography of Impact Studies ApendxiIV

Breastfeeding 

Promotion and Support

Fox, Mary Kay, Nancy Burstein, Jenny Golay, and others. WIC Nutrition 

Education Assessment Study: Final Report. Alexandria, Va.: U.S. 

Department of Agriculture, Food and Nutrition Service, 1999.

Wiemann, Constance M., Jacqueline C. DuBois, and Abbey B. Berenson. 

“Racial/Ethnic Differences in the Decision to Breastfeed Among 

Adolescent Mothers.” Pediatrics, Vol. 101, No. 6 (1998), pp. 11–23.

Timbo, Babgaleh, Sean Altekruse, Marcia Headrick, and others. 

“Breastfeeding Among Black Mothers: Evidence Supporting the Need for 

Prenatal Intervention.” Journal of the Society of Pediatric Nurses, Vol. 1, 

No. 1 (1996), pp. 35–46.

Balcazar, Hector, Catherine M. Trier, and Jose A. Cobas. “What Predicts 

Breastfeeding Intention in Mexican-American and Non-Hispanic White 

Women? Evidence From a National Survey.” Birth, Vol. 22, No. 2 (1995), pp. 

74–80.

Schwartz, J. Brad, Barry M. Popkin, Janet Tognetti, and others. “Does WIC 

Participation Improve Breast-Feeding Practices?” American Journal of 

Public Health, Vol. 85, No. 5 (1995), pp. 729–731.

Referrals Fox, Mary Kay, Nancy Burstein, Jenny Golay, and others. WIC Nutrition 

Education Assessment Study: Final Report. Alexandria, Va.: U.S. 

Department of Agriculture, Food and Nutrition Service, 1999.

McCunniff, Michael D., Peter C. Damiano, Michael J. Kanellis, and others. 

“The Impact of WIC Dental Screenings and Referrals on Utilization of 

Dental Services Among Low-Income Children.” Pediatric Dentistry, Vol. 20, 

No. 3 (1998), pp. 181–187.

Suarez, Lucina, Diane M. Simpson, and David R. Smith. “The Impact of 

Public Assistance Factors on the Immunization Levels of Children Younger 

Than 2 Years.” American Journal of Public Health, Vol. 87, No. 5 (1997), pp. 

845–848.
Page 26 GAO-01-442 Research on WIC Nutrition Services

Appendix V

Demonstration Studies: Major Findings, 

Scope, and Major Limitations ApendxiV

Study Major finding(s) Scope (timeframe) Major limitation(s)

Nutrition education

Abusabha and others, 

1998

Nutrition education lectures and facilitated group 

discussions were more effective than brochures at 

increasing participants’ nutrition knowledge. 

Facilitated group discussion was more effective 

than brochures at increasing participants’ 

confidence in performing specific nutrition related 

behaviors. 

Seven WIC clinics in 

New Mexico (not 

specified)

Missing data; 

selection bias 

Havas and others, 1998 Consumption of fruits and vegetables increased 

after an education program consisting of a series of 

three 45-minute group sessions taught by paid peer 

educators and incorporating special visual 

materials and a direct mailing to participants. 

Sixteen WIC clinics in 

Maryland (not 

specified)

Missing data; measurement 

error; inappropriate data 

analysis techniques

Breastfeeding

Gross and others, 1998 The duration of breastfeeding among AfricanAmerican WIC participants increased with peer 

counselor support or viewing promotional 

breastfeeding videos. 

Four WIC sites in 

Baltimore, Md. (1992–

1994)

Selection bias;

measurement error

Ahluwalia and others, 

2000

WIC participants increased the initiation of 

breastfeeding when exposed to (1) an enhanced 

education program with access to a hotline, (2) a 

free breast-pump loan program, (3) a hospitalbased program with bedside support and 

counseling after delivery, (4) community coalitions, 

and (5) peer counseling provided by former 

participants.

State of Georgia 

(1992–1996)

Missing data

Weimer, 1998 1. Breastfeeding initiation and duration rates 

increased after volunteer peer counseling.

2. Breastfeeding initiation and duration rates 

increased after paid peer counseling.

3. Duration of breastfeeding increased after 

postdelivery contact with mother in hospital 

was followed up with support (including home 

visits) by a specially trained paraprofessional.

4. Breastfeeding initiation and duration rates 

increased with culturally appropriate 

breastfeeding education provided in high 

school or WIC clinics.

1. Two communities 

in Iowa (not 

specified) 

2. Six counties in 

Michigan (not 

specified)

3. Five counties in 

North Carolina 

(not specified)

4. Local agency in 

Guam (not 

specified)

1. Missing data; selection bias

2. Lack of control group; 

missing data

3. Lack of control group

4. Selection bias

Reifsnider and Eckhart, 

1997

Duration of breastfeeding increased after prenatal 

nutrition education classes focusing on 

breastfeeding. 

WIC clinics in three 

rural Oklahoma 

counties (1986)

Lack of control group

Tuttle and Dewey, 1995 Breastfeeding initiation rates increased among 

Hmong WIC participants after a culturally sensitive 

prenatal breastfeeding class and prenatal and 

postpartum counseling. 

Seven WIC clinics in 

three California 

counties (1991–1992)

Selection bias;

measurement error
Appendix V

Demonstration Studies: Major Findings, 

Scope, and Major Limitations

Page 27 GAO-01-442 Research on WIC Nutrition Services

Shaw and Kaczorowski, 

1999

Breastfeeding initiation and duration increased after 

counseling and support provided by WIC 

participants, trained and paid as peer counselors.

WIC programs in nine 

West Tennessee 

health departments 

(1996–1997)

Measurement error

Grummer-Strawn and 

others, 1997

Clinics with paid peer counselors had higher rates 

of breastfeeding initiation than clinics without peer 

counselors. Clinics with a lactation specialist or 

consultant, and peer counselors, had higher rates 

of breastfeeding initiation than clinics with only peer 

counselors. However, the benefits of lactation 

specialists were offset when peer counselors spent 

at least 45 minutes with individual participants.

Fifty-one WIC clinics in 

Mississippi (1989–

1993)

Selection bias;

missing data

Referrals

Birkhead and 

others, 

1998

Children were 5.5 times more likely to be 

immunized, and immunized more rapidly, at WIC 

sites where staff escorted children to a pediatric 

clinic in the same facility for immunization. Children 

were almost 3 times more likely to be immunized, 

and immunized more rapidly, at sites with a 

voucher/check incentive. (Until immunization, a 

family must visit the clinic monthly, rather than 

every other month, to pick up WIC voucher/checks.) 

Six WIC sites in New 

York City (1991)

Lack of control group

Hoekstra and others, 

1998

Immunization rates increased at sites with a 

voucher/check incentive (until children are 

immunized, a family must visit the clinic monthly, 

rather than every 3 months, to pick up WIC 

voucher/checks). 

Nineteen WIC sites in 

Chicago (1996–1997)

Lack of control group; 

measurement 

error; inappropriate data 

analysis 

techniques

Hutchins and others, 

1999

Vaccinations increased at sites with vaccination 

screening and a voucher/check incentive (until 

immunization, a family must visit the clinic monthly, 

rather than every 3 months, to pick up WIC 

voucher/checks).

Seven WIC sites in 

Chicago (1991–1993) 

Inappropriate data analysis

 techniques; selection bias

(Continued From Previous Page)

Study Major finding(s) Scope (timeframe) Major limitation(s)
Page 28 GAO-01-442 Research on WIC Nutrition Services

Appendix VI

GAO Contacts and Staff Acknowledgments ApendxiVI

GAO Contacts Robert E. Robertson, (202) 512-7215

Thomas E. Slomba, (202) 512-9910

Staff 

Acknowledgments

In addition to those named above, Judy Hoovler, Sara Ann Moessbauer, 

Corrina Nicolaou, Judy Pagano, Debra Roush, and Eugene Wisnoski made 

key contributions to this report.

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Appendix VI

GAO Contacts and Staff Acknowledgments

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