(AL01-01-24) Improved Diet Quality From Early to Late Pregnancy Is Associated With Lower Gestational Weight Gain in Women With Obesity

Objectives: It is unclear how maternal diet impacts gestational weight gain (GWG) because prior studies focused on individual foods rather than diet quality and generally considered diet at single timepoints. Hence, we evaluated if improved diet quality across pregnancy was associated with GWG using two validated dietary indices.

Methods: At median 13 and 35 weeks gestation, 377 Illinois women completed 3-month semi-quantitative food frequency questionnaires to calculate the Healthy Eating Index (HEI)-2015 and Alternative Healthy Eating Index (AHEI)-2010 excluding alcohol (both out of 100 points). We calculated change in diet quality across pregnancy by subtracting diet quality scores at 13 weeks from those at 35 weeks. Using weight before pregnancy and at median 38 weeks gestation, we calculated gestational age- and pre-pregnancy BMI (ppBMI)-specific GWG z-scores (GWGz) using an international reference chart. We calculated ppBMI (kg/m²) from self-reported weight/height and classified women as having under-/normal weight ( < 25), overweight (25 – 29.9), or obesity (≥ 30). Adjusted for demographic/lifestyle factors including daily caloric intake, multivariable linear regression models evaluated whether improvement in HEI-2015 or AHEI-2010 across pregnancy was associated with GWGz and explored interactions with ppBMI.

Results: In women with relatively high socioeconomic status, median (25^th, 75^th percentile) HEI-2015, AHEI-2010, and GWGz were 64.8 points (58.7, 71.1), 51.8 points (44.5, 60.1), and 0.4 (-0.4, 1.1), respectively. In women with obesity, each 10-point improvement in HEI-2015 across pregnancy was associated with -0.55 (95% CI: -0.82, -0.27; p = 0.0001) lower GWGz, which drove overall associations. Increased intakes of vegetables and nuts/legumes were the major contributors to this relationship. We observed a similar association of AHEI-2010 with GWGz in women with obesity (β: -0.48; 95% CI: -0.81, -0.15; p = 0.005), driven by increasing intakes of greens/beans, whole grains, and seafood/plant protein but decreasing intake of refined grains across pregnancy.

Conclusions: Independent of dietary energy density, improved diet quality across pregnancy was associated with lower GWGz in women with obesity. Future studies may consider the implications of our findings for maternal/child health.

Funding Sources: NIEHS, NICHD, MSU AgBioResearch