Effect of Pregnancy Gingivitis on Maternal Saliva Microbiota

Pregnant women undergo a myriad of physiological changes, including important hormonal variations. Pregnancy gingivitis is a condition that affects up to 30% to 100% of women, is related to hormonal modifications, and could play an important role in gestational gut colonization and immunological training of the newborn. Nonetheless, oral health is not always included in routine prenatal care. In this study, we collected saliva samples of pregnant women with and without pregnancy gingivitis and analyzed the oral microbiota through 16S sequencing. In addition, meconium samples from the infants of participating women were analyzed. The oral microbiota of pregnant women with and without pregnancy gingivitis did not show significant differences in diversity. However, significant differences in microbiome composition were observed. Pathway analysis showed that, despite taxonomic similarity, the PG group had activated energy metabolism, bacterial growth, lipid metabolism, and virulence pathways with NOD-like receptor activation, indicating pro-inflammatory microbial activity. In contrast, the NPG group exhibited central metabolism and repair mechanisms, suggesting that PG could affect microbiome function rather than composition. In addition, it appears that the microbiome composition of offspring of mothers with gingivitis also differs from that of offspring from mothers without gingivitis, although the number of available samples did not allow for definite conclusions. As such, a larger cohort and deeper sequencing methods are needed to assess the oral microbiota of pregnant women with and without gingivitis and to explore the possibility of bacterial translocation from the maternal gingiva to the fetal gut.