The characteristics of intestinal flora in overweight pregnant women and the correlation with gestational diabetes mellitus

Objective: To investigate the characteristics of intestinal flora in overweight pregnant women and the correlation with gestational diabetes mellitus (GDM). Methods: A total of 122 women were enrolled and divided into four groups according to their pre-pregnancy BMI and the presence of GDM: Group 1 (n = 71) with a BMI <24 kg/m², without GDM; group 2 (n = 27) with a BMI <24 kg/m², with GDM; group 3 (n = 17) with a BMI ≥24 kg/m², without GDM; and group 4 (n = 7) with a BMI ≥24 kg/m² with GDM. Feces were collected on the day that the oral glucose tolerance test was conducted. The V3-V4 variable region of 16S rRNA was sequenced using the Illumina Hiseq 2500 platform, and a bioinformatics analysis was conducted. Results: There were differences between the four groups in the composition of intestinal flora, and it was significantly different in group 4 than in the other three groups. Firmicutes accounted for 36.4% of the intestinal flora in this group, the lowest among the four groups, while Bacteroidetes accounted for 50.1%, the highest among the four groups, making ratio of these two bacteria approximately 3:5, while in the other three groups, this ratio was reversed. In women with a BMI <24 kg/m², the insulin resistance index (homeostatic model assessment for insulin resistance (HOMA-IR)) in pregnant women with GDM was higher than in those without (P3 = 0.026). Conclusion: The composition of the intestinal flora of pregnant women who were overweight or obese before pregnancy and suffered from GDM was significantly different than women who were not overweight or did not suffer from GDM.