Strengths and Limitations
Strengths of this review include that both outcomes and methods were used to analyze the vaginal microbiome composition. We identified studies from multiple databases and assessed differences across studies at various decision points to analyze metagenomic data.
The heterogeneity across studies in methods and data reporting limited the ability to pool and re-analyze the data. This was further complicated by the fact that some studies reported most microbial taxa at solely the genus level, whereas other studies only included species-level data for specific genus like Lactobacillus . Furthermore, the format and availability of data associated with manuscripts also varied greatly (e.g., raw data versus including only taxonomy tables used in the analysis). In cases where the full microbial datasets were not available, it was difficult to determine whether the absence of GBS reporting was due to lack of detection, exclusion from analysis because of low abundance, or some other factor. These limitations highlight the importance of making study analysis code and raw data freely available upon publication in order to encourage reproducibility and comparison.