Dietary protein in early pregnancy and gestational diabetes mellitus: a prospective cohort study

Purpose The relationship between dietary protein intake and the risk of gestational diabetes mellitus (GDM) remains inconsistent and unclear. Here, we examined the correlation between the various sources of protein intake among Chinese pregnant women and GDM. Methods This prospective cohort study included 1060 pregnant women at 6–13 +6 weeks of gestation from Guangdong Provincial Hospital for Women and Children, South China. The participants’ intake of dietary protein was assessed using a validated quantitative food frequency questionnaire during the early trimester. GDM was diagnosed via an oral glucose tolerance test performed at 24–28 gestational weeks. Logistic regression analysis was used to evaluate the association between dietary protein intake during pregnancy and GDM. Furthermore, we applied restricted cubic splines to determine their linear relationship. Results About 26.3% ( n = 279) of pregnant women were diagnosed with GDM. Animal protein intake was revealed to have a positive correlation with GDM risk (Q4 vs. Q1: OR, 2.78; 95% CI, 1.46–5.34; P = 0.015), whereas high intake levels of dietary plant protein were linked to reduced GDM risk (Q4 vs. Q1: OR, 0.43; 95% CI, 0.25–0.73). In stratified analysis, the relationship between protein and GDM was stronger during early pregnancy in women with obesity. However, total protein intake did not show a significant association with GDM. Conclusions Our study findings suggest that a plant protein-based diet was associated with reduced GDM risk, whereas the dietary intake of animal protein was positively associated with GDM risk among Chinese women during early pregnancy.