Characterizing the Subgingival Microbiome of Pregnant African American Women.

OBJECTIVE: To generate preliminary data about the subgingival microbiome of pregnant African American women to calculate power for a future larger study and to explore associations among the microbiome, periodontal inflammation, and preterm birth.

DESIGN: Comparative descriptive pilot study design.

SETTING: Urban area in the southeastern United States.

PARTICIPANTS: Thirty-four African American women in the third trimester of pregnancy.

METHODS: Based on visual assessment, participants were placed in two groups: healthy gingiva and gingivitis. Saliva samples were analyzed for interleukin-1β (IL-1β), matrix metalloproteinase-8 (MMP-8), and C-reactive protein (CRP). DNA was extracted from subgingival plaque samples, and amplicons of the fourth hypervariable region were sequenced.

RESULTS: We found no differences in overall microbiome diversity between the healthy gingiva (n = 22) and the gingivitis (n = 12) groups although significant differences were found among the bacterial taxa present. The gingivitis group had greater levels of salivary IL-1β and MMP-8, whereas CRP was not different between groups. Overall microbiome diversity was positively associated with the CRP level. We found no significant relationships among the subgingival microbiome, periodontal inflammation, and preterm birth.

CONCLUSION: Gingivitis in pregnancy did not appear to shift the overall composition or diversity of the subgingival microbiome although differences in several bacterial taxa suggest that inflamed gingiva in pregnant women are associated with a disruption in the stability of the subgingival microbiome. A correlation between the abundance of bacteria and CRP also suggests an association between the microbiome and systemic inflammation. These findings provide support for future research about how the oral microbiome and progression of periodontal disease in pregnant women link with adverse pregnancy outcomes.