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. 2022 May 13;12(1):7926.
doi: 10.1038/s41598-022-12007-9.

The vaginal microbiome and the risk of preterm birth: a systematic review and network meta-analysis

Unnur Gudnadottir  1 , Justine W Debelius  2 , Juan Du  2 , Luisa W Hugerth  2   3 , Hanna Danielsson  2   4 , Ina Schuppe-Koistinen  2   3 , Emma Fransson  2   5 , Nele Brusselaers  2   6   7
Affiliations

The vaginal microbiome and the risk of preterm birth: a systematic review and network meta-analysis

Unnur Gudnadottir et al. Sci Rep. .

Abstract

Preterm birth is a major cause of neonatal morbidity and mortality worldwide. Increasing evidence links the vaginal microbiome to the risk of spontaneous preterm labour that leads to preterm birth. The aim of this systematic review and network meta-analysis was to investigate the association between the vaginal microbiome, defined as community state types (CSTs, i.e. dominance of specific lactobacilli spp, or not (low-lactobacilli)), and the risk of preterm birth. Systematic review using PubMed, Web of Science, Embase and Cochrane library was performed. Longitudinal studies using culture-independent methods categorizing the vaginal microbiome in at least three different CSTs to assess the risk of preterm birth were included. A (network) meta-analysis was conducted, presenting pooled odds ratios (OR) and 95% confidence intervals (CI); and weighted proportions and 95% CI. All 17 studies were published between 2014 and 2021 and included 38-539 pregnancies and 8-107 preterm births. Women presenting with "low-lactobacilli" vaginal microbiome were at increased risk (OR 1.69, 95% CI 1.15-2.49) for delivering preterm compared to Lactobacillus crispatus dominant women. Our network meta-analysis supports the microbiome being predictive of preterm birth, where low abundance of lactobacilli is associated with the highest risk, and L. crispatus dominance the lowest.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
PRISMA flowchart of selection of articles included in the network meta-analysis.
Figure 2
Figure 2
Forest plots showing all 17 included studies and the pooled and weighted proportion of “low-lactobacilli” women who delivered (a) preterm and (b) at term.
Figure 3
Figure 3
Network map of all 17 included studies by vaginal microbiome composition, showing how many studies reported which community state types (CSTs). Legend: Each dot represents a CST, with the number indicating how many studies reported it. The lines between the blue dots and their thickness represent the number of studies which reported the CSTs joined by the line.
Figure 4
Figure 4
Forest plots comparing community state types (CSTs) and their risk of preterm birth using (a) Lactobacillus crispatus and (b) “Low-lactobacilli” as reference group, where an odds ratio (OR) > 1.00 indicates association with preterm birth.
See this image and copyright information in PMC

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