Maternal and Neonatal Birth Outcomes

• Maternal participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) may be associated with a lower likelihood of inadequate gestational weight gain (Strength of evidence [SOE]: Low), lower alcohol use in pregnancy (SOE: Low), no difference in smoking during or after pregnancy (SOE: Low), no difference in perinatal death overall (SOE: Low), and lower risk of stillbirth in Black women (SOE: Low).
• Maternal WIC participation during pregnancy is likely to be associated with lower risk of preterm birth and lower risk of low birth weight infants (SOE: Moderate).
• The evidence was insufficient to determine whether maternal WIC participation was associated with decreased neonatal intensive care unit (NICU) stays.

Maternal Dietary Outcomes

• WIC participation during pregnancy may be associated with better diet quality and greater intakes of total fruit (SOE: Low).
• The evidence was insufficient to determine whether maternal WIC participation during pregnancy was associated with intake of other specific maternal nutrients.

Infant and Child Health Outcomes

• Maternal WIC participation during pregnancy is likely to be associated with reductions in infant mortality (SOE: Moderate).
• Maternal WIC participation may be associated with increased child preventive care visits and immunizations during the first year of life (SOE: Low).
• Child WIC participation may be associated with increased immunizations of children (SOE: Low).
• The evidence was insufficient to determine whether either maternal or child participation was associated with other child health outcomes including child mortality and morbidity.

Child Anthropometric Status or Growth

• The evidence was insufficient to determine whether child WIC participation was associated with weight status in children.

Breastfeeding Outcomes

• Maternal WIC participation is likely to be associated with no difference in breastfeeding initiation rates (SOE: Moderate).
• WIC participation may be associated with no difference in the introduction of solid foods before 4 months of age (SOE: Low).
• The evidence was insufficient to determine whether maternal or child WIC participation was associated with longer duration of breastfeeding or breastfeeding exclusivity.

Child Dietary Outcomes

• Child WIC participation is likely to be associated with better child diet quality and greater intakes of 100% fruit juice, whole grain cereals intake, and age-appropriate shifts from whole milk to lower fat milk (SOE: Moderate).
• Child WIC participation may be associated with higher intakes of vitamin D andiron, and for children 2 to 4 years, limiting saturated fat (SOE: Low).
• The evidence was insufficient to determine whether child WIC participation was associated with fruit or vegetable intakes.
• Household participation in WIC is likely to be associated with purchasing of healthy food groups and reduced purchasing of less healthy foods and beverages(SOE: Moderate).

Child Development and Academic Achievement

• Maternal WIC participation may be associated with higher cognitive development scores in early childhood (SOE: Low), no differences in measures of child communication and adaptive behavior in early childhood (SOE: Low), and no differences in measures of child social development in early childhood (SOE: Low).
• The evidence was insufficient to determine whether child WIC participation was associated with cognitive development or whether maternal or child WIC participation was associated with other child development outcomes.

Objectives. The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) aims to safeguard the health of low-income, nutritionally at-risk pregnant and postpartum women and children less than 5 years old. This systematic review evaluates whether participation in WIC is associated with nutrition and health outcomes for women, infants, and children, and whether the associations vary by duration of participation or across subgroups. Because of major revisions to the WIC food package in 2009, we prioritized studies published since 2009 and included studies comparing outcomes before and after the 2009 food package change.

Data sources. Using electronic publication databases, we conducted a literature search from January 2009 to September 2021 and a targeted search for selected outcomes from January 2000 to September 2021.

Review methods. Paired team members independently screened search results, serially abstracted data, assessed risk of bias, and graded strength of evidence (SOE) using standard methods for observational studies.

Results. We included 82 quantitative observational studies and 16 qualitative studies, with 49 studies comparing outcomes of WIC participants with WIC-eligible non-participants. WIC prenatal participation was associated with lower risk of three outcomes: preterm delivery (moderate SOE), low birth weight (moderate SOE), and infant mortality (moderate SOE). Prenatal WIC participation was associated with better maternal diet quality (low SOE), lower risk of inadequate gestational weight gain (low SOE), lower alcohol use in pregnancy (low SOE), and no difference in smoking (low SOE). Maternal WIC participation was associated with increased child preventive care and immunizations (each low SOE), and higher cognitive scores for children (low SOE). Child WIC participation was associated with better diet quality (moderate SOE), and greater intakes of 100 percent fruit juice, whole grain cereals, and age-appropriate milk (moderate SOE). Household WIC participation was associated with greater purchasing of healthy food groups (moderate SOE). Maternal WIC participation was not associated with breastfeeding initiation (moderate SOE). The evidence was insufficient for other outcomes related to maternal health and child growth. The evidence generally was insufficient on how WIC participation affects outcomes across subgroups.

Conclusions. Maternal WIC participation was associated with improved birth outcomes, lower infant mortality, and better child cognitive development. WIC participation was associated with purchasing healthier foods and with improved diets for pregnant women and children. More research is needed on maternal health outcomes; food security; child growth, development, and academic achievement; and effectiveness of WIC in all segments of the eligible population.

Caulfield LE, Bennett WL, Gross SM, Hurley KM, Ogunwole SM, Venkataramani M, Lerman JL, Zhang A, Sharma R, Bass EB. Maternal and Child Outcomes Associated With the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Comparative Effectiveness Review No. 253. (Prepared by the Johns Hopkins University Evidence-based Practice Center under Contract No. 75Q80120D00003.) AHRQ Publication No. 22-EHC019. Rockville, MD: Agency for Healthcare Research and Quality; April 2022. DOI: https://doi.org/10.23970/AHRQEPCCER253. Posted final reports are located on the Effective Health Care Program search page.