Gestational diabetes mellitus (GDM) significantly affects both maternal and neonatal health, yet its impact on the neonatal intestinal microbiota remains underexplored. A study analyzed meconium samples from 32 newborns, 16 from GDM-affected mothers and 16 from healthy controls, to assess the effects of maternal GDM on offspring microbiota. The microbiome analysis showed notable differences in microbiota composition in GDM-exposed neonates. Specifically, the GDM group exhibited a significant increase in the phylum Bacteroidetes, while there were significant reductions in Actinobacteria and Proteobacteria. At the genus level, opportunistic pathogens such as Bacteroides and Escherichia-Shigella were significantly more abundant in the GDM group. These results indicate that maternal GDM disrupts the initial colonization of the neonatal intestinal microbiota. The study suggests that interventions aimed at controlling maternal glycemic levels during pregnancy could help reduce the dysbiosis in offspring microbiota and address potential clinical consequences.