Maternal diet during pregnancy may influence obesity-related outcomes in both women and their children, but the effects may differ by outcome and by protein source. In the Danish National Birth Cohort, maternal diet, assessed around gestational week 25 was related to postpartum weight retention in mothers and to growth and overweight/obesity in offspring. Lower maternal protein intake, diluted by higher fat and/or carbohydrate intake, was associated with higher postpartum weight retention at 6 and 18 months. Paradoxically, higher total protein intake was associated with higher offspring BMI z-scores and higher risk of overweight/obesity at ages 7, 11 and 14 years. Protein source appeared to matter. Higher intake of poultry and fish protein was associated with lower risk of substantial postpartum weight retention and lower offspring overweight/obesity risk, whereas higher intake of red meat and dairy protein was associated with higher offspring overweight/obesity risk. Substitution analyses suggested that replacing red meat or dairy protein with poultry or fish protein was associated with lower obesity-related risk in both mothers and offspring.
Overall, our findings suggest that maternal protein intake during pregnancy cannot be viewed as uniformly beneficial or harmful. Rather, both the amount and source of protein, and the balance between protein, fat and carbohydrate, may be important. These results support a more nuanced view of maternal macronutrient composition during pregnancy and indicate that an optimal protein range may be needed to balance both maternal and offspring health. Current work is extending this framework to broader outcomes, including protein leverage hypothesis-related pathways and later cardiometabolic and cardiovascular disease risk.