Conclusion
Only a small proportion of vaginal microbiome studies reported the
presence of GBS during pregnancy. No systematic differences in factors
previously known to introduce bias in microbiome studies were associated
with the lack of GBS reporting. However, there was considerable
heterogeneity in research methods employed across studies. Consideration
of less abundant, but clinically meaningful microbes in vaginal
microbiome studies may improve our understanding of how the vaginal
microbiota influences pregnancy outcomes. GBS was reported in studies
across all trimesters of pregnancy using metagenomic methods, although
reporting of culture based GBS does not always correlate with
metagenomic GBS reporting. Therefore, studies evaluating the presence of
GBS may need to adopt both confirmatory testing for GBS via culture and
parallel comparison with results obtained from
metagenomic/meta-taxonomic approaches.