26: The cervicovaginal microbiota is different in women destined to have a preterm birth


      The importance of microbial communities to human health and disease is just now being revealed. For decades, the vaginal microbiota has been thought to contribute to preterm birth (PTB). However, there remains a paucity of data characterizing the cervico-vaginal (CV) microbiota in women destined to have a PTB.

      Study Design

      Using CV biospecimens from a prospective cohort of women at high risk for PTB, the microbiota at 20-24 weeks (V1) and at 24-28 weeks (V2) was analyzed in women who ultimately had a PTB (N=14) compared to those who had a term birth (N=32). Taxonomic assignment of 16S rRNA reads was done using Markov Chain taxonomy classifier. 128 phylotypes were identified in the 78 samples. Samples were clustered into community state types (CST) I, III and IV based on established nomenclature (Ravel et al., PNAS 2010). CSTs I are dominated by Lactobacillus crispatus and CST III by Lactobacillus inners. Samples of CST IV lack substantial number of different Lactobacillus spp. and have anaerobic bacteria. In order to identify phylotypes whose relative abundance is significantly different between samples, 0-inflated negative binomial models were fitted to the relative abundance data of 50 phylotype that were present in at least 25% of all samples.


      Proportion of CSTs differed at V1 and V2 in women destined to have a PTB compared to term (Fig 1). In analyzing all samples, CST proportions were significantly different in women who had a PTB (16.7, 61.1 and 22.2%) compared to term (35.0, 31.6, 33%)(P=0.012). Percent of non-CST III was significantly higher in samples from women delivering at term than in those with PTB (68% vs. 39%, P=0.002).


      The CV microbiota differs in the late 2nd and early 3rd trimester in women destined to have a PTB. The mechanisms by which altered microbiota promote preterm parturition require urgent investigation. Since microbiota can be manipulated through pre-and probiotics, targeting the microbiota for the prevention of PTB should become an active area of research.
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