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6 September 2022

Maternal, Infant, and Child Health Outcomes Associated With the Special Supplemental Nutrition Program for Women, Infants, and Children: A Systematic ReviewFREE

Publication: Annals of Internal Medicine
Volume 175, Number 10

Abstract

Background:

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is intended to improve maternal and child health outcomes. In 2009, the WIC food package changed to better align with national nutrition recommendations.

Purpose:

To determine whether WIC participation was associated with improved maternal, neonatal–birth, and infant–child health outcomes or differences in outcomes by subgroups and WIC enrollment duration.

Data Sources:

Search (January 2009 to April 2022) included PubMed, Embase, CINAHL, ERIC, Scopus, PsycInfo, and the Cochrane Central Register of Controlled Trials.

Study Selection:

Included studies had a comparator of WIC-eligible nonparticipants or comparison before and after the 2009 food package change.

Data Extraction:

Paired team members independently screened articles for inclusion and evaluated risk of bias.

Data Synthesis:

We identified 20 observational studies. We found: moderate strength of evidence (SOE) that maternal WIC participation during pregnancy is likely associated with lower risk for preterm birth, low birthweight infants, and infant mortality; low SOE that maternal WIC participation may be associated with a lower likelihood of inadequate gestational weight gain, as well as increased well-child visits and childhood immunizations; and low SOE that child WIC participation may be associated with increased childhood immunizations. We found low SOE for differences in some outcomes by race and ethnicity but insufficient evidence for differences by WIC enrollment duration. We found insufficient evidence related to maternal morbidity and mortality outcomes.

Limitation:

Data are from observational studies with high potential for selection bias related to the choice to participate in WIC, and participation status was self-reported in most studies.

Conclusion:

Participation in WIC was likely associated with improved birth outcomes and lower infant mortality, and also may be associated with increased child preventive service receipt.

Primary Funding Source:

Agency for Healthcare Research and Quality. (PROSPERO: CRD42020222452)
The US Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) was established in 1974 to serve eligible low-income women and children younger than age 5 years (1). The WIC program provides supplemental foods, nutrition education and breastfeeding support, screening and referrals to medical and social services, and support for high-risk pregnancies (2–5). In 2009, the WIC food package was changed to align with recommendations from the National Academies of Sciences, Engineering, and Medicine aimed at reducing diet-related chronic disease (6–8). Participation in WIC could potentially contribute to lower morbidity and mortality for mothers and infants, and reduce economic, racial, or ethnic disparities in adverse outcomes through its services addressing nutritional status and food security as well as its referrals facilitating receipt of preventive health care and other social services (9, 10).
In 2012, the US Department of Agriculture (USDA) published a report (2002 to 2010) that qualitatively synthesized results from studies on outcomes before the 2009 food package change (4); the report found evidence that WIC participation was associated with improved birth outcomes (for example, preterm birth) and child preventive care utilization, but could not draw conclusions on other maternal and child health outcomes. Our systematic review is part of a larger evidence report commissioned by the USDA to examine the most recent evidence (11). Here, we describe the findings related to the association of maternal, neonatal–birth, and infant–child health outcomes with WIC participation, including the effect of the 2009 food package change and whether the associations differ by participant characteristics or WIC enrollment duration.

Methods

With input from a technical expert panel and representatives from the Agency for Healthcare Research and Quality (AHRQ) and the USDA Food and Nutrition Service (FNS), we developed a protocol (Supplement 1), registered on PROSPERO. We followed the AHRQ Methods Guide for Effectiveness and Comparative Effectiveness Reviews and PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) reporting guidelines (12).

Data Sources and Searches

We searched PubMed, Embase, CINAHL, ERIC, Scopus, PsycInfo, and the Cochrane Central Register of Controlled Trials from 1 January 2009 to 19 April 2022 for studies on WIC participants compared with WIC-eligible nonparticipants after the 2009 food package change. We also searched back to 2000 for studies on infant mortality and maternal mortality because few studies addressed these outcomes. We hand-searched reference lists of systematic reviews and reports and searched the gray literature for relevant unpublished studies. Details of the search strategy can be found in Supplement A of Supplement 2.

Study Selection

We based study selection on the PICOTS (population, intervention, comparator, outcomes, timing of outcomes measurement, and setting) framework (Table 1 of Supplement 2). We required studies to have a WIC-eligible comparison group. A priori outcomes of interest included maternal mortality, maternal morbidity (gestational hypertension, anemia in pregnancy, preeclampsia, and gestational diabetes), maternal pregnancy outcomes (method of delivery, gestational weight gain, prepregnancy weight status, and postpartum weight retention), maternal health behaviors (smoking and alcohol use), maternal health care utilization (HIV testing, receipt of early prenatal care), birth and neonatal outcomes (fetal death, stillbirth and neonatal mortality, preterm birth, low birthweight, and neonatal intensive care unit [NICU] admission and hospital length of stay), and infant and child health outcomes (mortality, morbidity [health status and hospitalization], anemia, preventive care visits, and immunizations). Paired team members independently screened abstracts and full-text articles for eligibility, with differences resolved by consensus.

Data Extraction and Quality Assessment

Paired investigators sequentially extracted data on study characteristics, WIC program characteristics (for example, national, state, local agencies), participant characteristics, WIC eligibility and duration of participation, and results for each outcome. One reviewer completed abstraction for included studies, and a second reviewer checked for completeness and accuracy.
We used the EPHPP (Effective Public Health Practice Project) tool to assess the risk of bias (13). The summary assessment of the overall quality of each study (strong, moderate, or weak) was based on the tool's risk-of-bias domains: selection bias, appropriate adjustment for confounders (a measure taking into account both the existence of important differences in characteristics between intervention groups and, if so, percentage of relevant confounders that were controlled for), data collection methods, withdrawals, and dropouts (Table 2 and Table 3 of Supplement 2). Because WIC is a public health program without randomized controlled trials in the body of evidence, we further evaluated how confounding and risk adjustment were addressed. We rated the body of evidence as having “adequate” risk adjustment when most studies performed relevant covariate adjustment (threshold for adequate was adjustment for income [or limiting to Medicaid-eligible comparison group] and other sociodemographic variables, and health status for health-related outcomes). We rated the body of evidence as having “extensive” risk adjustment if it included studies that applied additional methods to address unmeasured confounders and selection bias related to the choice to participate in WIC, such as through analytic methods (for example, fixed-effects models). Study-specific covariates are included in Table 4 to Table 32 of Supplement 2. We did not formally assess reporting bias because of the lack of reliable methods for identifying reporting bias in observational studies.

Data Synthesis and Analysis

We graded the strength of evidence (SOE) using the grading scheme recommended by the AHRQ Methods Guide for Conducting Comparative Effectiveness Reviews (14). We considered 4 domains in assigning evidence grades for the body of evidence by outcome: study limitations across all studies (high, medium, or low, corresponding to the EPHPP risk of bias–study quality assessment ratings of weak, moderate, and strong, respectively), directness of the evidence, consistency across studies, and precision of effect estimates. We considered SOE for studies with “direct evidence,” which contained the main comparison of interest (WIC participants compared with WIC-eligible nonparticipants). We evaluated the consistency of the “direct evidence” with “indirect evidence,” which was from natural experiment designs that assessed the association of the 2009 WIC food package change with outcomes. We assigned the final evidence grade by evaluating and qualitatively considering the assessments of the above domains and the overall assessment of results across studies into 4 categories: high, moderate, low, and insufficient. The interpretation of moderate SOE is that the findings are likely to be stable, but some doubt remains, whereas low SOE indicates additional evidence is needed before concluding that the findings are stable (14). Insufficient SOE indicates that that we cannot reach a conclusion due to no evidence, inability to estimate an effect, or no confidence in the estimate effect for this outcome. All SOE grades are fully defined in Table 33 of Supplement 2 and the full report (11).
We summarized the results for each outcome because meta-analyses were deemed not appropriate, owing to the small number and marked heterogeneity of studies. Results for all studies are presented in the tables, with select studies highlighted in the text to provide context, particularly for outcomes with low or moderate SOE ratings.

Role of the Funding Source

The USDA funded the review through an interagency agreement with AHRQ. Neither agency had a direct role in selecting or assessing studies but did review and offer feedback on the protocol and the synthesis of the evidence.

Results

The Figure shows a summary of our evidence search and study selection. Of the 20 included observational studies, 19 reported direct evidence: 7 cohort (15–21), 11 cross-sectional (22–32), and 1 case–control (33). One study reported indirect evidence from an evaluation of the effect of the 2009 food package change on outcomes among WIC participants compared with the general population (34). Four studies addressed maternal health outcomes, 8 studies addressed birth–neonatal outcomes, and 8 studies addressed infant–child health outcomes (Table 1). Table 2 summarizes the evidence by outcome, providing details about SOE assessment, including the adequacy of risk adjustment. Tables 4 through 32 of Supplement 2 are complete evidence tables.
Figure. Evidence search and selection: PRISMA flow diagram.
* The number of citations in the exclusion box exceeds the total because citations could be excluded for more than 1 reason (that is, reviewers did not need to agree on reason for exclusion).
Table 1. Characteristics of the Studies Addressing Health Outcomes
Table 2. Summary of Evidence on Association of Maternal or Child WIC Participation With Maternal, Neonatal and Birth, and Infant and Child Health Outcomes

Association of WIC and Maternal Health Outcomes in Pregnancy and Postpartum

Maternal Mortality and Morbidity

No eligible studies examined maternal mortality. No studies provided direct evidence for maternal morbidity outcomes. One study of the 2009 food package change provided indirect evidence on preeclampsia and gestational diabetes, but given its indirect nature, we determined the evidence was not sufficient to draw conclusions (34).

Maternal Pregnancy Outcomes

One single-state study (21) provided direct evidence on gestational weight gain using birth-certificate data (2004 to 2013; n = 269 528 observations). In maternal fixed-effects models adjusting for several relevant confounders, among Medicaid enrollees, WIC participation (vs. nonparticipation) was associated with a 3.13% (SE, 0.45%) lower likelihood of “less than recommended weight gain.” We concluded that WIC participation may be associated with a lower likelihood of inadequate gestational weight gain, based on 1 study with medium study limitations and extensive risk adjustment to address confounding (low SOE) (Table 2).

Maternal Health Behaviors and Health Care Utilization

One national cross-sectional study using the Pregnancy Risk Assessment Monitoring System (1992 to 2013; n = ∼230 000 women) reported no association between WIC participation and smoking during pregnancy or postpartum (22). In the same study, WIC participation was associated with less alcohol use during pregnancy (22). We concluded that WIC participation may be associated with lower alcohol use in pregnancy and no difference in smoking during or after pregnancy, based on 1 study with medium study limitations and adequate risk adjustment (low SOE) (Table 2). One cross-sectional study demonstrated higher self-reported HIV testing rates for WIC participants (30), but the evidence was insufficient to draw conclusions given that it was a single study with high limitations (insufficient SOE) (Table 2).

Differences in Association Between WIC Participation and Maternal Health Outcomes by Duration of Participation or Participant Characteristics

Three studies assessed the association of maternal health outcomes by race and ethnicity subgroups (19, 21, 34). A single-state cohort study (2004 to 2013; n = 275 482 women) showed that WIC participation was associated with lower likelihood of inadequate weight gain overall, and in both Black women (−3.49% adjusted mean change; SE, 0.65%) and White women (−2.64% adjusted mean change; SE, 0.62%) (21). We concluded that maternal WIC participation may be associated with lower inadequate gestational weight gain for Black and White women, based on this single study with medium limitations and adequate risk adjustment (low SOE).
One retrospective cohort study examined data on singleton live births (20 to 44 weeks' gestation) (2007 to 2012; n = 2 963 888 mothers). Participation in WIC was associated with reduced risk for late entry (>6 months' gestation) into prenatal care with a similar association across racial and ethnic subgroups (19). We concluded that maternal WIC participation may be associated with lower risk for late presentation for prenatal care for Black, White, Hispanic, and Asian women, based on evidence from a single study with medium limitations and adequate risk adjustment (low SOE) (Table 2).

Association of Maternal WIC Participation with Birth and Neonatal Outcomes

Fetal Death, Stillbirth, and Neonatal Mortality

One large cohort study reported direct evidence on the association between WIC participation and fetal death, stillbirth, and neonatal mortality (death within 28 days after delivery) (15). This study from California (2010; n = 236 564 mothers) (15) did not find a statistically significant association between WIC participation and perinatal death (hazard ratio, 0.89 [95% CI, 0.78 to 1.02]). There may be no association between maternal WIC participation and perinatal death, based on this single study with medium limitations and adequate risk adjustment (low SOE) (Table 2).

Preterm Birth

Two cohort studies (15, 17) and 1 cross-sectional study (25) provided direct evidence on preterm birth, and 1 study of the 2009 food package change (34) provided indirect confirmatory evidence. One large national cohort study (2011 to 2017; n = 11 148 261 mothers) provided direct evidence showing that WIC participation (vs. no participation) was associated with lower odds (0.88; CI, 0.86 to 0.87) of preterm birth (17). We concluded that maternal WIC participation is likely to be associated with reduced risk for preterm birth and with longer gestation, based on 3 studies with consistent findings and overall medium limitations and adequate risk adjustment across all 3 studies (moderate SOE) (Table 2).

Infant Low Birthweight

One cohort study (15) and 3 cross-sectional analyses (24, 25, 31) provided direct evidence on low birthweight, and the 2009 food package change study (34) reported indirect confirmatory evidence. One large, single-state, retrospective cohort study (2010; n = 236 564 income-eligible women) showed that WIC participation (vs. no participation) was associated with lower risk for low birthweight (hazard ratio, 0.81 [CI, 0.69 to 0.97]) (15). One cross-sectional analysis (2004 to 2012; n = 102 079) showed that WIC participation among women with Medicaid was associated with a 2.5% (P < 0.01) decrease in the probability of low birthweight after many adjustments (that is, 24% risk reduction) (25). Another cross-sectional analysis (2022; n = 9083 children) in immigrant families reported lower odds of low birthweight (odds ratio [OR], 0.79 [CI, 0.65 to 0.97]) with maternal WIC participation (vs. no participation) (31). We concluded that maternal WIC participation is likely to be associated with reduced risk for low birthweight infants, based on evidence from 3 studies with consistent findings that taken together had medium limitations and adequate risk adjustment (moderate SOE) (Table 2).

NICU Admission

The SOE was deemed insufficient to draw conclusions about NICU admission due to evidence provided by only 1 single-state, cross-sectional study with high limitations (25).

Differences in Association between WIC Participation and Neonatal and Birth Outcomes by Duration of Participation or Participant Characteristics

One nested case−control study identified stillbirth case patients and live-born control participants (2006 to 2008; n = 549 live births and 262 stillbirths). In the Medicaid-restricted sample, WIC was protective against stillbirth for Black women (adjusted OR, 0.23 [CI, 0.09 to 0.59]), but not White women (adjusted OR, 2.11 [CI, 0.75 to 5.95]). Among Hispanic women, 1 analytic model revealed elevated odds of stillbirth associated with WIC participation (adjusted OR, 2.16 [CI, 1.06 to 4.37]) but other models did not consistently show this finding (33). Maternal WIC participation may be associated with lower risk for stillbirth in Black women, based on 1 study with medium limitations reporting a clinically important association that was precise and robust across analyses (low SOE), but findings for other racial and ethnic groups were imprecise and inconsistent (insufficient SOE) (33).
One retrospective cohort study, linking California Medicaid and WIC participation data (2010; 236 564 women), showed no dose–response relationship between perinatal death and trimester of WIC initiation, but evidence was insufficient to draw a conclusion (15).
Three studies (2 with direct and 1 with indirect evidence) assessed the association of preterm birth with WIC by race and ethnicity (17, 25, 34). One cohort study showed that WIC participation was associated with similarly decreased risk for preterm birth across racial and ethnic subgroups (17). We concluded with low SOE that the association between WIC participation and preterm birth may not vary by race or ethnicity based on 2 studies with direct evidence, medium limitations, and relatively precise estimates.
Two studies (1 with direct and 1 with indirect evidence) assessed the association of WIC and infant low birthweight by race and ethnicity (25, 34). The SOE was insufficient to determine whether the association between WIC participation and low birthweight differed by race or ethnicity due to conflicting results and lack of high-quality, direct evidence. One cross-sectional study (25) showed that WIC participation among Black and White mothers was associated with a comparable decrease in the probability of NICU admission. The SOE was insufficient to determine whether the association between WIC participation and NICU admission differed by race or ethnicity due to evidence from only a single study with high limitations. One cross-sectional study (31) of immigrant families showed similar associations between maternal WIC participation and infant low birthweight by maternal length of stay in the United States, but the SOE was insufficient, as there was only 1 study with high limitations.

Association of Maternal or Child WIC Participation With Infant and Child Health Outcomes

Infant Mortality

Two studies reporting direct evidence showed that maternal WIC participation was associated with reduced odds of infant mortality, defined as death of a child younger than 1 year of age (17, 28). One large national cohort study using birth-certificate data (2011 to 2017; n = 11 148 261) reported lower adjusted odds of infant mortality for WIC live births (vs. eligible non-WIC live births) (adjusted OR, 0.84 [95% CI, 0.83 to 0.86]) (17). A cross-sectional analysis (1994 to 1995; 2763 singleton infants in Puerto Rico) also showed lower odds of infant mortality associated with WIC participation in pregnancy (28). We concluded that maternal WIC participation is likely associated with lower infant mortality, based on evidence from 2 studies with consistent findings, with overall medium study limitations and adequate risk adjustment (moderate SOE) (Table 2).

Child Mortality, Morbidity, and Anemia

No eligible studies reported on child mortality or anemia. One cross-sectional study (2000 to 2010; n = 29 650 children up to 36 months of age) evaluated whether child WIC participation attenuated the adverse effects of childhood stressors (defined as household food insecurity and maternal depressive symptoms) on child health status and hospitalization (29). Participation in WIC attenuated the association between these stressors and caregiver-reported “fair-poor child health status,” but did not impact the association between stressors and child hospitalization (25). The SOE was insufficient to draw conclusions due to high study limitations and because the study did not directly examine the association between WIC participation and these outcomes (Table 2).

Infant and Child Health Care Utilization

Two cross-sectional studies used National Immunization Survey data and examined the association of child WIC participation with immunization receipt (26, 27). One study (2007 to 2011; n = 13 183) found that children up to 24 months of age enrolled in WIC were more likely to have received routine child immunizations (vs. former recipients or eligible nonparticipants) (27). The second study (2013; n = 13 460) demonstrated that current or former WIC participation was associated with reduced odds of 2 or more missed opportunities for hepatitis A vaccination (adjusted OR, 0.59 [95% CI, 0.45 to 0.77]) (26). Child WIC participation may be associated with immunization receipt, based on evidence from 2 studies with consistent findings, high study limitations, and adequate risk adjustment (low SOE) (Table 2).
Maternal prenatal WIC participation was found to be associated with greater well-child visit utilization in the first year of life (adjusted difference in number of well-child visits, 0.20 [CI, 0.16 to 0.23]) in 1 large cohort study (2004 to 2103; n = 290 377 women) (20). Prenatal WIC participation was also associated with a small positive difference in the probability of receiving any vaccination in the first year of life (1.36%; SE, 0.365; P < 0.01) (20). Maternal WIC participation may be associated with child preventive care receipt (both well-child visits and immunizations), based on this single study with medium limitations with adequate risk adjustment (low SOE) (Table 2). One cross-sectional study (2020; n = 10 356) demonstrated lower odds of receiving childhood preventive dental care visits for non-WIC participating children, compared with WIC participants (adjusted OR, 0.56 [95% CI, 0.41 to 0.83]), but the SOE was deemed insufficient to draw conclusions because the study had high limitations (32) (Table 2).

Differences in Association Between WIC Participation and Infant and Child Health Outcomes by Duration of Participation or Participant Characteristics

No studies addressed differences in the association of maternal WIC participation with infant and child health outcomes by gestational age at enrollment or duration of participation. One large national cohort study (2011 to 2017; n = 11 148 261 birth certificates) reported no differences in the association between maternal WIC participation and reduced risk for infant mortality across different racial and ethnic subgroups (17). The SOE was deemed low because the evidence was from 1 study with medium limitations but precise estimates and adequate risk adjustment.

Discussion

This systematic review not only synthesized recent evidence supporting the effect of WIC on maternal, neonatal–birth, and infant–child health outcomes but also highlighted important gaps in our knowledge. The aim of WIC is to enhance the health and nutrition of low-income pregnant women through several mechanisms, including nutrition education, provision of supplemental foods, referral to prenatal care and other services, and support for high-risk pregnancies (9, 10). There are some established pathways through which maternal participation in WIC could improve maternal health and birth and neonatal outcomes. We found moderate SOE that maternal WIC participation is likely to be associated with lower risk for preterm birth, low birthweight, and infant mortality. For low birthweight and preterm birth, although findings were consistent with prior reviews (4, 35), the magnitude of risk reductions (11% to 24% for low birthweight, and 10% to 15% for preterm delivery) is more modest than those reported previously (10% to 40% reduction in low birthweight in prior reviews) (4, 35). Differences in these estimates could be attributed to differences in study design (including adjustment for confounding factors) and temporal changes in other factors impacting these outcomes, such as access to and timing of prenatal care (36), access to programs such as the Supplemental Nutrition Assistance Program (37), Medicaid expansion (38), and demographics of the pregnant population (39). Despite differences in estimates, the evidence consistently supports a positive association of WIC with birth and neonatal outcomes, which could have important individual and population health benefits, given the short- and long-term adverse effects of preterm birth and low birthweight on infant and child health (40). Furthermore, the evidence suggests that WIC participation might also reduce health care costs associated with low birthweight and preterm birth (15, 41, 42).
We also found new evidence that maternal WIC participation is likely to be associated with a lower risk for infant mortality. The magnitude of risk reduction varied in the 2 studies reviewed, potentially reflective of temporal changes associated with the populations studied (14% in a national study of Medicaid births from 2011 to 2017 [17] vs. 40% risk reduction in an older study from Puerto Rico [1994 to 1995] [28]). Although the SOE for this association was rated as moderate, indicating that the conclusion could be strengthened by additional high-quality evidence, these findings still underscore the importance of WIC as a part of the country's public health infrastructure.
In addition to these important findings, we identified large gaps in evidence about the effect of maternal WIC participation on maternal or birth–neonatal outcomes. We found no studies that reported on the association of WIC participation with maternal mortality and no studies with direct evidence that reported on maternal morbidity. This evidence gap is consistent with earlier reviews (4, 35). We found low SOE that WIC participation was associated with lower likelihood of inadequate gestational weight gain (21, 34). We identified studies suggesting that differences in adverse birth outcomes and infant mortality associated with WIC vary by race or ethnicity, with a greater risk reduction in adverse outcomes for Black women. More evidence is needed to evaluate whether WIC participation may provide differential benefits by race and ethnicity; this is important, as maternal mortality, morbidity, and birth and neonatal outcomes are pressing public health issues characterized by important income, racial, and ethnic disparities (43, 44).
We also found a paucity of recent evidence with regard to infant and child health outcomes. We did find low SOE that maternal and child WIC participation may be associated with increased receipt of child immunizations (26, 27). These findings are consistent with evidence reported in prior reviews (4). Referrals for children for pediatric preventive care are part of the WIC model and may represent the mechanism for increasing receipt of immunization (45, 46). Selection bias may exist because those who choose to enroll in a safety-net program like WIC may also be more likely to use other recommended health care (or social) services (47). For other important child health outcomes, we found no evidence or insufficient evidence to draw conclusions. Notably, we did not find any studies that examined child mortality as an outcome. Our findings highlight gaps in evidence that persist from the prior review (4), which found mixed and inconclusive evidence for outcomes such as anemia.
The evidence has several limitations. First, all evidence is from observational studies, and potential risk of bias due to residual confounding is a major limitation of such studies. To our knowledge, there are no analytic methods that exist for systematic review synthesis that can help overcome these limitations. Second, studies had potential for selection bias related to whether an income-eligible mother or child elects to participate in WIC; there are unmeasurable differences between groups that chose to participate versus those that did not. Most studies did not use analytic approaches that could help to address this bias (such as propensity scoring, instrumental variables, or examination of consecutive pregnancies or sibling-matched pairs) (48). Third, many studies depended on self-report of WIC participation, without further information on participation (such as duration or nature of benefits received), leading to potential misclassification bias. Fourth, due to the paucity of studies, heterogeneity of study designs, and outcome measurement, we could not synthesize findings via meta-analysis.
Overall, this review highlights the need for higher-quality evidence on the association of maternal and child WIC participation with maternal, infant, and child health outcomes. We found only 20 studies that fulfilled our rigorous study inclusion criteria for these specific outcomes, including our requirement that studies use a WIC-eligible comparison group to reduce selection bias. In some areas, the evidence was absent and in others, the SOE was moderate or low. Stronger analytic methods should be used in observational studies to improve the strength of available evidence. Also, for maternal health outcomes, investigators should develop a comprehensive research agenda, examining maternal mortality, maternal morbidity (inclusive of anemia, preeclampsia, gestational diabetes, gestational hypertension), maternal pregnancy outcomes (such as gestational weight gain and postpartum weight reduction), and maternal health care utilization during pregnancy and postpartum. A similar comprehensive approach is required for growing the evidence base for infant and child health outcomes. Part of this approach could also include examining the spillover effect of WIC participation on other household members (other children, for example). Recent pandemic-related changes to the program, such as remote service delivery, remote benefit access, and food package substitution waivers, should also be examined for their effect on health outcomes. Studies should also endeavor to determine the differential effect of WIC on outcomes by participant characteristics as well as duration and timing of participation, given the potential for WIC to reduce disparities in maternal, infant, and child health outcomes (10).

Supplemental Material

Supplement 1. Study Protocol

Supplement 2. Supplementary Material

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Information & Authors

Information

Published In

cover image Annals of Internal Medicine
Annals of Internal Medicine
Volume 175Number 10October 2022
Pages: 1411 - 1422

History

Published online: 6 September 2022
Published in issue: October 2022

Keywords

Authors

Affiliations

Maya Venkataramani, MD, MPH https://orcid.org/0000-0002-2805-2035
Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.V., S.M.O.)
S. Michelle Ogunwole, MD, PhD https://orcid.org/0000-0001-9479-7695
Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.V., S.M.O.)
Center for Human Nutrition, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland (L.E.C., K.M.H., J.L.L.)
Ritu Sharma, BSc
Center for Evidence-Based Practice, Johns Hopkins University School of Medicine, Baltimore, Maryland (R.S., A.Z.)
Center for Evidence-Based Practice, Johns Hopkins University School of Medicine, Baltimore, Maryland (R.S., A.Z.)
Susan M. Gross, PhD, MPH, RDN https://orcid.org/0000-0003-1589-2307
Department of Population, Family and Reproductive Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland (S.M.G.)
Kristen M. Hurley, MPH, PhD
Center for Human Nutrition, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland (L.E.C., K.M.H., J.L.L.)
Jennifer L. Lerman, MPH, RDN https://orcid.org/0000-0003-2705-8643
Center for Human Nutrition, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland (L.E.C., K.M.H., J.L.L.)
Division of General Internal Medicine and Center for Evidence-Based Practice, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.B.B.)
Wendy L. Bennett, MD, MPH https://orcid.org/0000-0001-9828-0706
Division of General Internal Medicine, Johns Hopkins University School of Medicine, and Department of Population, Family and Reproductive Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland (W.L.B.).
Disclaimer: The authors of this manuscript are responsible for its content. Statements in the manuscript do not necessarily reflect the official views of or imply endorsement by AHRQ or the U.S. Department of Health & Human Services (HHS).
Acknowledgment: The authors would like to thank AHRQ Task Order Officers Jill S. Huppert, MD, MPH, and Anjali Jain, MD, and USDA FNS representatives Alexander Bush, MPH, and Ruth Morgan, MPH, for feedback and insights on this review. The following technical experts provided input on the systematic review: Linda Alexander, MD, MPP; William H. Dietz, MD, PhD; Nancy Krebs, MD; Angela Odoms-Young, PhD; Emily Petersen, MD; Daniel J. Raiten, PhD; Jackson P. Sekhobo, PhD, MPA; Shannon E. Whaley, PhD; and Parke Wilde, PhD. The technical expert panel members were offered a small honorarium in appreciation of their time.
Grant Support: By contract number 75Q80120D00003 task order 75Q80120F32003 from the AHRQ, HHS.
Reproducible Research Statement: Study protocol: Available in Supplement 1. Statistical code and Data set: Not available.
Corresponding Author: S. Michelle Ogunwole, MD, PhD, Johns Hopkins University School of Medicine, 2024 East Monument Street, Suite 2-638, Baltimore, MD 21205; e-mail, [email protected].
Author Contributions: Conception and design: M. Venkataramani, L.E. Caulfield, A. Zhang, S.M. Gross, K.M. Hurley, E.B. Bass, W.L. Bennett.
Analysis and interpretation of the data: M. Venkataramani, S.M. Ogunwole, L.E. Caulfield, A. Zhang, S.M. Gross, K.M. Hurley, J.L. Lerman, E.B. Bass, W.L. Bennett.
Drafting of the article: M. Venkataramani, S.M. Ogunwole, L.E. Caulfield, R. Sharma, K.M. Hurley, J.L. Lerman, W.L. Bennett.
Critical revision of the article for important intellectual content: M. Venkataramani, L.E. Caulfield, R. Sharma, A. Zhang, S.M. Gross, E.B. Bass, W.L. Bennett.
Final approval of the article: M. Venkataramani, S.M. Ogunwole, L.E. Caulfield, R. Sharma, A. Zhang, S.M Gross, K.M. Hurley, J.L. Lerman, E.B. Bass, W.L. Bennett.
Statistical expertise: L.E. Caulfield, A. Zhang, W.L. Bennett.
Obtaining of funding: E.B. Bass, W.L. Bennett.
Administrative, technical, or logistic support: R. Sharma, A. Zhang, J.L. Lerman, E.B. Bass.
Collection and assembly of data: M. Venkataramani, S.M. Ogunwole, L.E. Caulfield, R. Sharma, A. Zhang, S.M. Gross, K.M. Hurley, J.L. Lerman, W.L. Bennett.
This article was published at Annals.org on 6 September 2022.
* Drs. Ogunwole and Venkataramani contributed equally to this work.

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Maya Venkataramani, S. Michelle Ogunwole, Laura E. Caulfield, et al. Maternal, Infant, and Child Health Outcomes Associated With the Special Supplemental Nutrition Program for Women, Infants, and Children: A Systematic Review. Ann Intern Med.2022;175:1411-1422. [Epub 6 September 2022]. doi:10.7326/M22-0604

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