Ecological succession links mother-infant oral microbiota colonization across the first six months of life.

OBJECTIVE

This study evaluated salivary cytokine profiles and characterized longitudinal salivary microbiome dynamics in 27 mother-infant dyads, from third trimester of pregnancy through 1, 3, and 6 months postpartum.

METHODS

Mother-infant dyads were prospectively recruited according to predefined inclusion/exclusion criteria. Maternal oral health outcomes were assessed using standardized DMFT and CPI indices, supported by socioeconomic and dietary questionnaire. Saliva samples were subjected to multiplex bead-based assays for cytokine quantification and microbiome profiles were generated using 16S rRNA sequencing. Potential confounding factors were assessed due to their influence on early-life oral microbiome development.

RESULTS

Despite mid-level socioeconomic backgrounds mothers exhibited a high prevalence of dental caries (77.8%) and periodontal alterations (59.2%). Salivary maternal microbiome alpha-diversity remained temporal stable and significantly higher than that of infants (p < 0.05). Infant microbiomes showed early variability and exhibited greater similarity to maternal profiles by six months (beta-diversity, p < 0.05). Infant early communities were dominated by Streptococcus, followed by increases in Prevotella, Veillonella, and Rothia. Cariogenic genera persisted throughout infancy, whereas periodontal-associated taxa (Aggregatibacter, Fusobacterium) declined and were absent by six months. Distinct cytokine patterns were observed between mothers and infants, with consistent differences in IL-8 and IL-12 and time-dependent differences in IFN-γ, IL-10, IL-13, and IL-1β.

CONCLUSIONS

These findings highlight a dynamic ecological succession of the infant salivary microbiome and are consistent with the concept of early-life microbial imprinting within the context of maternal-infant interactions and shared environmental exposures. The early persistence of cariogenic taxa reinforces the importance of maternal oral health interventions during this critical developmental window.

CLINICAL SIGNIFICANCE: Early-life oral microbiome development is associated with maternal oral health and may reflect maternal-infant microbial sharing, with persistence of cariogenic taxa. This highlights the need for preventive dental care during pregnancy and early postpartum, in order to reduce infant risk and promote healthier oral microbiome trajectories.