Association of Maternal WIC Participation with birth and neonatal outcomes

In 2012, a report was published by the US Department of Agriculture (USDA) that reviewed the results of studies on the impact of WIC on pregnant women from 2002 to 2010 (before the 2009 food package change). There was strong evidence of an association between participation in WIC program and improved birth outcomes, including preterm births. This previous report could not draw evidence on other maternal outcomes and child health. This systematic review explores whether WIC participation is associated with improved maternal, neonatal-birth, and infant–child health outcomes. It is part of a larger evidence report commissioned by USDA to explore the most recent data on this subject.

Participation in the WIC program during pregnancy is likely associated with a lower risk of preterm birth, low birth weight, and infant mortality

Out of nearly 5,000 publications, 20 observational studies were included for analysis. Some studies show that pregnant women participating in WIC appear to have a lower risk of preterm birth, low birth weight and infant mortality with moderate strength of evidence (SOE).

• Maternal WIC participation and preterm birth :
  A nationwide cohort study conducted between 2011 and 2017 of nearly 11 150 000 mothers show that participation in the WIC program was associated with a lower likelihood of preterm birth and longer gestation (Soneji S, 2019). Another cohort study and a cross-sectional study confirm these findings (Fingar, 2017 ; Hamad, 2019).

• Maternal WIC participation and infant low birthweight :
  The 5 studies reviewed on this subject all point in the same direction and show a lower probability of low birth weight when pregnant women benefit from the WIC program. For example, a retrospective cohort study conducted on nearly 240,000 women shows a lower risk of low birth weight for women benefiting from the WIC program compared to those who do not (Fingar, 2017).

• Maternal WIC participation and infant mortality :
  New evidence shows that maternal WIC participation is likely to be associated with a lower risk for infant mortality, defined as death of a child younger than 1 year of age. For example, one large national cohort study using birth-certificate data (2011 to 2017; n= 11,148,261) reported lower adjusted odds (OR=0.84) of infant mortality for WIC live births (vs. eligible non-WIC live births) (adjusted OR, 0.84 [95% CI, 0.83 to 0.86]) (Soneji, 2019).

In this systematic review, no studies examined the association of WIC participation with maternal mortality nor direct evidence on maternal morbidity.

A positive association between WIC and birth and neonatal outcomes was consistently found and supported by evidence. As preterm birth and low birth weight have important short- and long-term negative effects on infant and child health, this could have important health benefits on individual and more largely, on population, (Nuyt, 2017). Evidence also suggests that WIC participation may consequently reduce health care costs associated with low birth weight and preterm birth (Fingar, 2017 ; Nianogo, 2019).

Maternal participation in the WIC program may be associated with a lower likelihood of inadequate gestational weight gain

WIC participation was associated with lower likelihood of inadequate gestational weight gain (low SOE). WIC studies show that adverse birth outcomes could vary by race/ethnicity with greater risk reduction for black women. More evidence is needed to evaluate whether WIC participation may provide differential benefits by race and ethnicity.

However, higher-quality evidence are further needed to confirm the association of WIC participation with maternal, infant, and child health outcomes. In addition, to improve the strength of available evidence in observational studies, stronger analytic methods should be used.