ACE and gestational diabetes: Comparing GDM vs. control groups, the ACE indices were higher (395.15 ± 10.56 vs. 356.27 ± 8.47, P = 0.029), and Chao indices were also higher (397.67 ± 10.24 vs. 361.32 ± 8.87, P = 0.040) in GDM (Figure 1), indicating that placental microbiota in GDM pregnancies had greater diversity and community richness at OTU level.