A WIC shopper pushes a stroller down the aisle of a Washington D.C. grocery store. A new study led by NST researchers analyzes whether the program supports healthy gestational weight gain. Photo courtesy of USDA
For nearly 60 years, the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) has supported low-income pregnant, postpartum, and breastfeeding women and young children with free food, nutrition education, and referrals to other health and family support services. While prior studies have documented how program participation improves health outcomes for women and children, research examining the program’s impact on a pregnant mother's weight is relatively sparse.
To determine whether the program is doing enough to support healthy gestational weight gain (GWG), UC Berkeley professor Susana Matias and former postdoctoral researcher Caitlin French, now an assistant project scientist at the Nutrition Policy Institute, analyzed birth records from more than 1 million pregnancies of WIC-eligible women. Their study, which was published in the June issue of Current Developments in Nutrition, found that most US women from low-income households remain at risk of gaining too little or too much weight during pregnancy.
Matias, the study’s lead author and an assistant professor of Cooperative Extension in the Department of Nutritional Sciences and Toxicology, said the findings could guide opportunities to improve maternal health through the WIC program.
“Nearly half of all pregnant women in the United States gain excessive weight during pregnancy, which could lead to maternal complications and obesity in the offspring,” she said. “Conversely, studies have identified associations between gaining too little weight and preterm delivery or giving birth to babies who are smaller than expected for their gestational age.” WIC serves close to a million pregnant women from low-income households per year, and as the only federal nutrition supplementation program that serves the mother-child dyad, it offers an opportunity to support those at potentially higher risk of unhealthy weight, starting during prenatal life.
Past studies on WIC participation and weight gain often examined the total weight a woman gained during pregnancy, a figure that the authors note could be skewed by the length of the pregnancy. The authors chose to use a standardized measure of GWG—calculated by comparing a woman’s weight gain during pregnancy to the expected weight gain for someone with her pre-pregnancy body mass index and gestational age at delivery—to provide a more accurate snapshot of weight gain. WIC participants were compared to eligible non-participants using propensity score weighting to address potential differences in demographic, health, and geographic factors that may have influenced program participation.
The authors found a small association between participating in WIC during pregnancy and reduced risk of low gestational weight gain, and that the program’s current benefits and services have little effect on curbing excessive GWG. To better understand these findings, the authors pointed to WIC participants’ reports of having inconsistent discussions with healthcare providers about weight gain and lack of knowledge about different gestational weight goals based on prepregnancy weight status, as shown in previous qualitative studies.
Some WIC-approved food items are in a WIC participant's shopping basket at a Detroit, Michigan, grocery store. Photo courtesy of USDA
The study findings suggest that the WIC food packages (which support the specific nutritional needs of women and children at various life stages) and cash value benefit (CVB)—the most popular program benefit—partially addressed limited caloric intake among some pregnant participants. However, the benefits did not seem to displace the consumption of cheaper foods that are higher in fat, sodium, and sugar, which results in weight gain.
Matias notes that increasing the dollar amount of the CVB would increase access to healthier foods among WIC-eligible women. Strengthening linkages between WIC and the health care sector could also improve maternal health outcomes. Matias points to the results of a pilot study in Maryland, which showed that pregnant women who received integrated WIC and obstetric care services gained roughly 10 pounds less than those who received the standard care.
“The most important thing to keep in mind is the continuum of maternal and child health,” said Matias. “By investing to support healthy pregnancies, we are supporting the health of the next generation.”
The study was supported by the RIDGE Partnership, with funding from the USDA Economic Research Service and Food and Nutrition Service.
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