No strong evidence of the protein leverage hypothesis in pregnant women with obesity and their infants

Objective: The goal of this study was to investigate the role of dietary protein on macronutrient and energy intake, maternal adiposity during pregnancy, and infant adiposity at birth.

Methods: In 41 women with obesity, early-pregnancy (13-16 weeks) protein intake was assessed with food photography and expressed as a ratio of Estimated Average Requirements (EAR) in pregnancy for protein (0.88 g/kg/d), herein "protein balance." Energy intake was measured by the intake-balance method, gestational weight gain as grams per week, and fat mass by a three-compartment model. Spearman correlations and linear models were computed using R version 4.1.1 (p < 0.05 considered significant).

Results: Women had a mean (SD) age of 27.5 (4.8) years and a pregravid BMI of 34.4 (2.9), kg/m² , and the majority were non-White (n = 23, 56.1%). Protein balance in early pregnancy was not significantly associated with energy intake across mid and mid/late pregnancy (β = 328.7, p = 0.30 and β = 286.2, p = 0.26, respectively) or gestational weight gain (β = 117.0, p = 0.41). Protein balance was inversely associated with fat mass in early, mid, and late pregnancy (β = -10.6, p = 0.01, β = -10.4, p = 0.03, β = -10.3, p = 0.03, respectively). Protein balance did not predict infant adiposity at birth (p > 0.05).

Conclusions: Low protein intake may have been present before pregnancy, explaining early relationships with adiposity in this cohort. The protein leverage hypothesis is likely not implicated in the intergenerational transmission of obesity.