↓ alpha-diversity, ↑ Proteobacteria. and Actinobacteria and ↓ Bacteroidetes in GDM newborns. Several phyla found in controls were absent in GDM newborns. Bacteria in GDM_A2 newborns did not show variation compared to controls, which might be attributed to the additional intervention by insulin. Here, INS is linked to gestational diabetes.