Interrogating Components of 2 Diet Quality Indices in Pregnancy using a Supervised Statistical Mixtures Approach

Abstract

Background: The Healthy Eating Index (HEI)-2015 and Alternative Healthy Eating Index (AHEI)-2010 evaluate diet holistically in pregnancy. However, it remains unclear how individual index components interact to contribute to health.

Objectives: To evaluate associations of HEI-2015 and AHEI-2010 components with gestational length using traditional and novel statistical methods in a prospective cohort.

Methods: Pregnant women completed a 3-mo food-frequency questionnaire (FFQ) at median 13 wk gestation to calculate the HEI-2015 or AHEI-2010. Covariate-adjusted linear regression models evaluated associations of HEI-2015 and AHEI-2010 total scores and individual components (one at a time and simultaneously adjusted) with gestational length. Covariate-adjusted weighted quantile sum regression models evaluated 1) associations of HEI-2015 or AHEI-2010 components as mixtures with gestational length and 2) contributions of components to these associations.

Results: Each 10-point increase in HEI-2015 and AHEI-2010 total score was associated with 0.11 (95% CI: -0.05, 0.27) and 0.14 (95% CI: 0.00, 0.28) wk longer gestation, respectively. In individual or simultaneously adjusted HEI-2015 models, higher intakes of seafood/plant proteins, total protein foods, greens/beans, and saturated fats but lower intakes of added sugars and refined grains were associated with longer gestational length. For the AHEI-2010, higher intake of nuts/legumes and lower intake of sugar-sweetened beverages (SSBs)/fruit juice were associated with longer gestational length. Jointly, 10% increases in HEI-2015 or AHEI-2010 mixtures were associated with 0.17 (95% CI: 0.001, 0.34) and 0.18 (95% CI: 0.05, 0.30) wk longer gestational length, respectively. Seafood/plant protein, total protein foods, dairy, greens/beans, and added sugars were the largest contributors to the HEI-2015 mixture. Nuts/legumes, SSBs/fruit juice, sodium, and DHA/EPA were the largest contributors to the AHEI-2010 mixture. Associations were less precise but consistent in women with spontaneous labors.

Conclusions: Compared to traditional methods, associations of diet index mixtures with gestational length were more robust and identified unique contributors. Additional studies could consider interrogating these statistical approaches using other dietary indices and health outcomes.

Keywords: AHEI-2010; HEI-2015; WQSR; diet mixtures; gestational length; pregnancy.

FIGURE 1

Associations of (A) HEI-2015 and (B) AHEI-2010 total score and cumulative mixture with gestational length in the full sample and among women with spontaneous labor. Data are presented as the change in gestational length (wk) for each 10-point increase in total score or 10% increase in mixture (95% CI). Linear regression models evaluated associations of HEI-2015 and AHEI-2010 total scores with gestational length. Weighted quantile sum regression models evaluated associations of HEI-2015 and AHEI-2010 components as a mixture with gestational length. All models accounted for age, prepregnancy BMI, total daily calories in early gestation, race/ethnicity, annual household income, educational attainment, smoking in the first trimester, pregnancy intention, marital status, employment status, and conception season. Abbreviations: AHEI-2010, Alternative Healthy Eating Index-2010; HEI-2015, Healthy Eating Index-2015.

FIGURE 2

Relative percentage of repeated holdouts with weights above the threshold for associations of HEI-2015 components as a mixture with gestational length in the (A) full sample and (B) among women with spontaneous labor. Each dot is a weight from one repeated holdout, whereas boxplots present the distributions of weights for each HEI-2015 component from 100 repeated holdouts with diamonds representing the mean. Notable contributors are those with mean weights (yellow diamonds) above the black horizontal threshold line (7.7%). Models accounted for age, prepregnancy BMI, total daily calories in early gestation, race/ethnicity, annual household income, educational attainment, smoking in the first trimester, pregnancy intention, marital status, employment status, and conception season. Abbreviations: HEI-2015, Healthy Eating Index-2015; WQSR, weighted quantile sum regression.

FIGURE 3

Relative percentage of repeated holdouts with weights above the threshold for associations of AHEI-2010 components as a mixture with gestational length in the (A) full sample and (B) among women with spontaneous labor. Each dot is a weight from one repeated holdout, whereas boxplots present the distributions of weights for each AHEI-2010 component from 100 repeated holdouts with diamonds representing the mean. Notable contributors are those with mean weights (orange diamonds) above the black horizontal threshold line (10.0%). Models accounted for age, prepregnancy BMI, total daily calories in early gestation, race/ethnicity, annual household income, educational attainment, smoking in the first trimester, pregnancy intention, marital status, employment status, and conception season. Abbreviations: AHEI-2010, Alternative Healthy Eating Index-2010; SSB, sugar-sweetened beverage; WQSR, weighted quantile sum regression.