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

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.