(213) Maternal Lactobacillus crispatus abundance in early gestation associated with decreased incidence of preterm birth

Although Lactobacillus spp. are prevalent members of the vaginal and gut microbiomes, their role in birth outcomes has received little attention. Recently, L. crispatus has been associated with decreased risk of spontaneous PTB. Lactoplantibacillus plantarum has also been implicated in attenuating the somatotropic axis, indicating a potential role in PTB outcomes. We sought to determine the role of the six most prevalent Lactobacilli spp. of the microbiome on birth outcomes in a large, prospective, longitudinal cohort (BaBs, Bacteria and Birth study).

Study Design:  The BaBs study prospectively enrolled gravidae (n=585) at risk for preterm birth at 11-19 6/7 wks, and longitudinally sampled maternal and applicable neonatal infant sites to 1mo postpartum. Sampling timepoints included enrollment, early 3^rd trimester (27-28wks), delivery (term or preterm), and within 6wks postpartum. A total of 52116 maternal and 14350 neonatal/infant samples were collected and subjected to metagenomics sequencing (MGS) and rigorous bioinformatics analysis for delineation of species via taxonomic classification of human filtered read counts using kraken2, TaxonKit, and bitTools.

Results:

A total of n= 328 subjects delivered at term, and n= 78 preterm, and n=179 were lost to followup/ dropout. Comparisons across timepoints revealed a statistically significant higher relative abundance of L.crispatus was present as early as 11 weeks in births destined to deliver at term ( >37 weeks), but not preterm. This was true for the number of L.crispatus MGS reads in not only the vaginal posterior from the initial visit (11-20 weeks) & early 3rd trimester (27-29wks), but in the oral microbiome and stool (Figure); these findings persistent post-partum.

Conclusion:

In the largest longitudinal microbiome in pregnancy study to date, L. crispatus dominated microbiome communities in the vagina, oral and gut, from the first trimester were protective and predicted term birth. This was unique to Lactobacillus crispatus, indicating a likely functional role for this beneficial microbe in early gestation and successful gestation to term.