Abstract: Objective  To evaluate the dietary protein intake of pregnant women in Beijing area and explore the relationship between the intake frequency of dietary protein in the first trimester and gestational diabetes mellitus (GDM). Methods  A retrospective study was conducted on the data involving 10 320 healthy singleton pregnant women from the Beijing Birth Cohort Study. All participants visited Beijing Obstetrics and Gynecology Hospital, Capital Medical University within 6-16 weeks of gestation from September 2018 to December 2020. Food frequency questionnaire (FFQ) was used to collect their dietary protein intake information in the first trimester. The 75g oral glucose tolerance test (OGTT) was conducted at 24 to 28 weeks of gestation, and GDM was diagnosed according to the criteria of the International Association of the Diabetes and Pregnancy Study Groups (IADPSG). The Chi-square test or ANOVA was used to analyze the relationship between general information and the incidence of GDM. Multivariable Logistic regression analysis was used to investigate the relationship between the intake frequency of dietary protein and GDM. Results  ①Totally 15.4% (1 585/10 320) women were diagnosed with GDM in this study. ②The univariate analysis showed that the intake frequencies of total dietary protein, animal protein and red meat were associated with the incidence of GDM (P<0.05), the higher intake frequencies of them, the higher incidence of GDM; However, the intake frequencies of plant protein and white meat did not (P>0.05). Among the red meat category, the higher intake frequencies of pork, the higher incidence of GDM (P<0.05). ③The multivariate Logistic regression analysis showed that after adjusting for confounding factors such as maternal age, level of education, parity, pre-pregnancy body mass index (BMI) and family history of diabetes, the increased intake frequencies of total dietary protein in the first pregnancy increased the risk of GDM (OR=1.504, 95% CI: 1.138-1.988, P <0.05). Among them, the intake frequencies of animal protein were associated with the incidence of GDM (OR=1.429. 95% CI: 1.122-1.984, P <0.05), whereas the intake frequencies of plant protein were not. Further, the increased intake frequencies of red meat increased the risk of GDM (OR=1.288, 95% CI:1.072-1.547, P<0.05), while no differences in the occurrence of GDM were noted between women with the different intake frequencies of white meat. Among the red meat category, the increased intake frequencies of pork increased the risk of GDM (OR=1.025, 95%CI: 1.007-1.044, P<0.05). Conclusions  The main source of dietary protein for Beijing pregnant women in the first trimester was animal protein, and the main source of meat was red meat. The increased intake frequencies of animal protein, especially for red meat and pork, were risk factors of GDM incidence, while the intake frequencies of white meat and plant protein were not associated with GDM incidence. Health education and guidance should be promoted early in pregnancy, even before pregnancy, for primary prevention of GDM incidence. 

Key words: the first trimester of pregnancy, animal protein, red meat, gestational diabetes mellitus