Associations between Participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) and Maternal Diet Quality.

Background: An objective of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is to improve maternal diet quality, but its effectiveness remains unclear. Better understanding how WIC participation shapes women's diet quality is crucial given that maternal diet plays a critical role in determining mothers' and children's short- and long-term overall health.

Objectives: This study aimed to compare the diet quality of WIC-participating women to WIC-eligible nonparticipating women and higher-income pregnant and postpartum women using a nationally representative sample.

Methods: This was a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2011-2018 cycles. Women aged 20 to 44 with at least one 24-h recall and complete data on pregnancy and postpartum status and WIC participation were included (n = 626). Diet quality was evaluated using the Healthy Eating Index-2015 (HEI-2015). Multivariable Tukey-adjusted linear models were used to compare HEI-2015 total and component scores between groups. Models were adjusted for age, pregnancy and postpartum status, breastfeeding status, race and ethnicity, and food security.

Results: Most women were postpartum and not pregnant (75%), nonbreastfeeding (60%), identified as non-Hispanic White (58%), and food secure (64%). WIC participants, WIC-eligible nonparticipants, and income-ineligible women had mean Total HEI-2015 scores of 52.7 (95% confidence interval [CI]: 50.6, 54.8), 54.2 (95% CI: 51.6, 56.7), and 55.0 (95% CI: 51.8, 58.2), respectively. There were no differences between groups for total and most component scores. Income-ineligible women had better Fatty Acids scores (5.7; 95% CI: 5.0, 6.4) than WIC participants (4.7; 95% CI: 4.1, 5.3; P < 0.05). WIC-eligible nonparticipants had better Refined Grains scores (6.0; 95% CI: 5.3, 6.6) than WIC participants (5.0; 95% CI: 4.4, 5.6; P < 0.05).

Conclusions: Overall diet quality was similar across WIC and income groups. Lower HEI-2015 component scores for WIC participants compared with WIC-eligible nonparticipants warrant further exploration. Research evaluating WIC's impact on maternal diet quality is needed to ensure continued support for low-income women's health.