Maternal protein intake during pregnancy and obesity risk in mothers and offspring: a prospective cohort study

BACKGROUND: The optimal dietary macronutrient composition during pregnancy to mitigate obesity risk in mothers and offspring remains unclear.

OBJECTIVES: This study aims to assess associations between maternal dietary macronutrient composition and obesity outcomes in mothers and offspring.

METHODS: We analyzed 66,360 singleton pregnancies from the Danish National Birth Cohort, with dietary intake assessed at gestational week 25. Outcomes included maternal postpartum weight retention (PPWR) at 6 and 18 mo and offspring's birth weight, risks of small for gestational age (SGA) and large for gestational age (LGA), body mass index (BMI) z-scores, and overweight/obesity (OWOB) risk at ages 7, 11, and 14 y. Mixture models with response surface visualization examined interactive macronutrient associations, and mixed restricted cubic splines assessed potential nonlinear relationships between maternal protein intake and obesity outcomes.

RESULTS: Mean maternal macronutrient compositions were 15.2% protein, 30.2% fat, and 54.1% carbohydrate. Response surfaces revealed that maternal lower protein intake (%), diluted by higher fat and/or carbohydrate, was associated with higher maternal PPWR at 6 and 18 mo but lower birth weight and BMI z-scores in offspring at ages 7, 11, and 14 y. Mixed restricted cubic splines indicated nonlinear associations between maternal protein intake (%) and SGA risk (nonlinear P = 0.003) and LGA (nonlinear P = 0.04), with a threshold around 15% protein; below this, SGA risk increased whereas LGA risk decreased. Linear associations were observed for risks of substantial PPWR (PPWR >5 kg) and childhood OWOB risk (nonlinear P > 0.05). Each 5% higher protein intake during pregnancy was related to a lower risk of substantial PPWR at 6 mo (odds ratio: 0.90; 95% confidence interval: 0.85, 0.95) and 18 mo (0.88; 0.82, 0.94) but higher risks of OWOB at ages 7 y (1.07; 1.01, 1.15) and 11 y (1.11; 1.03, 1.18), with no association at 14 y (1.02; 0.95, 1.10).

CONCLUSIONS: Higher maternal protein intake during pregnancy was associated with lower PPWR and SGA risk but higher LGA and childhood OWOB risks, highlighting potential trade-offs in maternal and offspring obesity outcomes.