“…Further evidence for an oral-placental axis involved in PTB includes the identification of common oral pathogens (e.g. Fusobacterium nucleatum , Dialister spp., Prevotella spp., and Porphyromonas gingivalis ) in the placenta of women with periodontal disease [ 84 , 85 ], which is associated with increased risk of PTB [ 84 , 86 , 87 ]. However, interventions that improve periodontal health during pregnancy do not prevent PTB [ 88 – 90 ] and many bacterial species that were historically considered to be limited to the oral cavity are now recognised as being commonly observed members of the vaginal niche.…”