Better Outcomes for Moms, Babies With Healthier WIC Foods

-Study suggests "policies to improve maternal nutrition may be an effective strategy to prevent preeclampsia," researchers say

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CME Author: Vicki Brower

Study Authors: Rita Hamad, Daniel F. Collin, et al.; Maureen M. Black, et al.

Target Audience and Goal Statement:

Obstetricians/gynecologists, pediatricians, internists, family medicine specialists, endocrinologists, public health specialists

The goal of the study was to determine whether the revised Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package improved birth and perinatal outcomes among recipients compared with the older WIC package.

Questions Addressed:

  • Are there concrete improvements in the health of mother and infant since the introduction in 2009 of the new WIC package?
  • There are weaknesses in the new package, and if so, where and what can be done to improve outcomes?

Action Points

  • Updates to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) package that incorporated more fruits and vegetables appeared to improve both maternal and infant health outcomes.
  • Understand that while the new WIC program improved a range of measures of better health for infants and mothers, substantial challenges remain, including critical under-enrollment of participants who could benefit, and remaining health disparities regarding race/ethnicity.

Study Synopsis and Perspective

Updates to the WIC package that incorporated more fruits and vegetables seemed to improve both maternal and infant health outcomes compared with the older program, according to an analysis of women and infants in California.

The study was designed to investigate whether changes to WIC, which were made in 2009, benefited more than 2 million mother-baby pairs in measures of eclampsia, gestational diabetes, gestational weight, infant gestational age, birth weight, and hospitalizations, explained Rita Hamad, MD, PhD, of the University of California San Francisco, and colleagues.

The nutritional changes to the program increased access to healthier foods, including whole foods such as whole grains, fruits, vegetables, and low-fat milk, they wrote in JAMA Pediatrics.

The researchers reported lower rates of preeclampsia after the revised WIC food package was introduced (-0.6 percentage points, 95% CI -0.8 to -0.4), and there was less excess weight gain during pregnancy (-3.2 percentage points, 95% CI -3.6 to -2.7).

The effects on infants born to mothers receiving the updated package were smaller, but still beneficial. The infants tended to have higher average gestational ages at birth (difference 0.2 weeks, 95% CI 0.001-0.034), were less likely to be small for gestational age (-0.4 percentage points, 95% CI -0.7 to -0.1), and were less likely to have birth weights under 2,500 g (-0.2 percentage points, 95% CI -0.4 to -0.004).

"Our study provides quasi-experimental evidence suggesting this association may be causal and that policies to improve maternal nutrition may be an effective strategy to prevent preeclampsia," they stated.

Hamad's group collected data from the California Office of State Health Planning and Development database of pregnant women who experienced at least half of their pregnancy after the package revision. They then compared outcomes with women who were pregnant before the revision took place, and accounted for general population-level trends by assessing outcomes in women who did not participate in the program.

In total, the researchers included 2,897,537 infants born to 2,441,658 mothers in their study. Compared with non-enrolled women, more mothers in the WIC program were Hispanic (68% vs 26%, respectively), and fewer had more than a high school education (25% vs 73%). They were also younger (26 vs 30 years), and tended to have more children.

Although black women were more likely than white women to deliver very low birth weight infants (<1,500 g), the majority of health outcomes were not significantly different for black versus white mothers and infants, Hamad said.

The authors also found that Hispanic and Asian women were more likely than white mothers to have reduced gestational weight gain, and were also more likely to have heavier infants of a greater gestational age, the authors reported.

However, they acknowledged "the burden of adverse birth outcomes and infant mortality is born disproportionately by black women," and concluded that taken together, the findings suggest these particular revisions to the program did not influence these associations.

"If we are able to show -- and future studies can confirm -- this modest revision to the food package had this kind of impact, that would suggest we need to be testing more robust, richer benefits," Hamad told MedPage Today. "The root of the nutrition problem is income inequality and bigger societal forces, so we can continue to address nutritional programs, but if we want to think about the big picture in making lasting, population-level impacts for pregnant women and their kids, then we should be thinking about policy changes."

The authors operated under the assumption that WIC participants and non-participants would not significantly differ in these outcomes if the package had not been revised; parallel trends during the pre- and post-revision period indicated that this assumption was true, they noted. Still, the 2008-2009 recession, for example, could have confounded the results, contributing to negative health effects of women in this population, they said.

Other limitations included an inability to rule out the possibility of an association between gestational diabetes and preterm birth with the WIC food package updates, a finding that "should be interpreted cautiously," they wrote.

Finally, the study lacked data for mother-child pairs beyond 2012, and did not have information regarding when mothers enrolled in the WIC program.

Source References: JAMA Pediatrics 2019; DOI: 10.1001/jamapediatrics.2019.1706

Editorial: JAMA Pediatrics 2019; DOI: 10.1001/jamapediatrics.2019.1682

Study Highlights: Explanation of Findings

Introduced in the 1970s, the WIC program was designed to provide nutritional support, educational resources, and referrals to health services for low-income pregnant and postpartum women and their young children. However, it had not been updated in nearly 3 decades. In October 2009, the program was revised to allot more dollars towards whole grains, vegetables, and low-fat milk, with the goal of reducing rates of obesity and corresponding chronic conditions.

The authors described the overall goal of the WIC program as a countermeasure against this by saying, "transmission of disadvantage during pregnancy may help explain the intergenerational persistence of health disparities in the United States."

They reviewed 2.4 million linked birth certificate and hospital discharge data from California from 2007 t0 2012, and found that WIC participation "was associated with post-2009 reductions in preeclampsia; in excess of maternal gestational weight gain, and in small-for-gestational-age (SGA) infants, large-for-gestational -age infants, and LBW infants," explained Maureen Black, PhD, of the University of Maryland School of Medicine in Baltimore, and colleagues in an accompanying editorial.

In subgroup analyses, Hamad's group found that there were racial/ethnic differences in birth weight, and in associations between WIC participation and birth weight. Changing these adverse outcomes associated with such differences "will require consideration of additional factors," the editorialists wrote.

They suggested focusing on three issues:

  • Identifying subgroups who are most likely to benefit from the revised WIC package, such as women with nutritional risk factors (i.e., anemia)
  • Under-enrollment of pregnant women in WIC, as nearly 50% of the eligible women across the country did not enroll in the program, "illustrating a gap between availability of program benefits and use"
  • Understanding that the benefits of promoting mother and child health impacts the entire society by lowering health costs, and more

"The benefits of promoting maternal and infant health affect the entire society by reducing health care costs, ensuring that infants avoid the negative health and developmental consequences associated with prenatal growth restriction, and increasing the likelihood that infants reach their developmental potential and achieve high human capital," the editorialists wrote.

The study's findings "contribute to science and policy," they noted, although it would be useful for future studies to identify which subgroups of pregnant women, like those with anemia or other risk factors, may best benefit from WIC enrollment. It would also be constructive to determine what prevents women from enrolling, they added.

"For example, prior work has found that WIC counselors offer disparate counseling to white and black women and that Hispanic women are more likely than black women to reside in close proximity to WIC-approved stores, concerning for structural racism embedded in the clinical and community contexts," Hamad and colleagues wrote.

Last Updated July 29, 2019
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