Major Dietary Protein Sources during Pregnancy and Obesity Risk in Mothers and Offspring: A Prospective Cohort Study

Maternal protein intake during pregnancy may influence long-term obesity risk in mothers and offspring, but the role of specific dietary protein sources remains unclear.

To examine associations of major dietary protein sources during pregnancy with maternal postpartum weight retention (PPWR) and offspring overweight/obesity, and to evaluate isocaloric substitution between sources.

In 59,791 mothers from the Danish National Birth Cohort (1996-2002), diet at gestational week 25 was assessed by a validated food-frequency questionnaire. Log-binomial regression and isocaloric substitution models estimated adjusted relative risks (RRs) for maternal PPWR >5 kg at 6-18 months postpartum and offspring overweight/obesity at ages 7-11 years.

Overall, 10,678 (22.1%) mothers had PPWR >5 kg and 8,287 (19.0%) offspring developed overweight/obesity. Comparing highest with lowest quintile of intake (% energy), higher total plant (RR 0.86; 95% CI 0.81, 0.91), grain (0.87; 0.82, 0.91), legume and nut (0.93; 0.88, 0.98), poultry (0.90; 0.85, 0.95), and fish protein (0.90; 0.86, 0.95) were associated with lower maternal PPWR risk, whereas higher red meat protein intake with higher risk (1.11; 1.05, 1.17). For offspring overweight/obesity, higher total animal (1.12; 1.05, 1.19), red meat (1.06; 1.00, 1.13), and dairy protein (1.11; 1.04, 1.17) were associated with higher risk, whereas poultry (0.95; 0.89, 0.99) and fish protein (0.93; 0.88, 0.99) with modestly lower risk. Replacing 1% of energy from total animal protein with plant protein, or from red meat or dairy protein with poultry, fish, or grain protein, was associated with 4-6% lower maternal PPWR risk; corresponding substitutions with poultry or fish protein were associated with 3-4% lower offspring risk.

During pregnancy, substituting poultry or fish protein for red meat or dairy protein was associated with lower risks of both maternal PPWR and offspring overweight/obesity, supporting consideration of protein source in food-based dietary guidance.