Fig. 1

Quantitative PCR of bacterial 16S rRNA gene abundance in pilot study samples and blank controls. Quantitative PCR was performed on DNA extracts from blank controls (Blk; N = 13) placenta (Plac; N = 35), vagino-rectal swabs (VRS; N = 16), cord blood (Crd bld; N = 16), and maternal blood (Mat bld; N = 16) from the pilot study. a VRS samples were significantly (ρ < 0.0001, ***) different from placenta, maternal and cord blood, and blank controls as measured by ANOVA followed by Tukey’s test. b Analysis of the low biomass samples in the absence of the very high biomass VRS samples, using ANOVA followed by Tukey’s, showed that placental samples had a significantly higher bacterial biomass than the other samples (ρ < 0.01, **)