Vaginal & gut microbiota diversity in pregnant women with bacterial vaginosis & effect of oral probiotics: An exploratory study

Background & objectives: The vaginal microbiota undergoes subtle changes during pregnancy and may affect several aspects of pregnancy outcomes. There has been no comprehensive study characterizing the gestational vaginal and gut microbiota and the dynamics of the microbiota with oral probiotics among Indian women. Hence, the study was aimed to explore the microbiota of pregnant women with normal microbiota and bacterial vaginosis (BV) environments and the effect of oral probiotics on the microbiota and the BV status in these women. Methods: Using high-throughput Illumina-MiSeq sequencing approach, the 16S rRNA gene amplicons were analyzed and the vaginal and gut microbiota of pregnant women with and without BV and pre- and post-probiotics (Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14) intervention for a month was characterized. Results: The study revealed a compositional difference in the vaginal and gut microbiota between BV and healthy pregnant women. The vaginal microbiota of healthy women was characteristically predominated by Lactobacillus helveticus, followed by L. iners and L. gasseri; in contrast, women positive for BV harboured higher alpha-diversity and had lower abundance of L. helveticus. Similarly, Prevotella copri, a gut microbe, associated with normal environment was detected in the vaginal samples of all pregnant women without BV, it remained undetected in women with the infection, while all women with BV had Gardnerella vaginalis, which decreased significantly with probiotic treatment. Gut microbiota also revealed dominant abundance of P. copri in healthy women, whereas it was significantly lower in women with BV. The bacterial clade, P. copri abundance increased from 9.17 to 16.49 per cent in the probiotic group and reduced from 7.75 to 4.84 per cent in the placebo group. Interpretation & conclusions: This study showed gestational vaginal and gut microbiota differences in normal and BV environments. With probiotic treatment, the dynamics of L. helveticus and P. copri hint towards a possible role of probiotics in modulating the vaginal microbiota.