The Role of the Vaginal Microbiome in Preterm Premature Rupture of Membranes: A Comprehensive Review of Mechanisms and Clinical Implications.

Background and Aims: Preterm premature rupture of membranes (PPROM), a complication in approximately 4.5% of pregnancies, is a leading cause of preterm birth and significant perinatal morbidity. A substantial body of evidence implicates vaginal dysbiosis a departure from a healthy, Lactobacillus-dominant microbiome in the pathogenesis of PPROM. This review synthesizes the current understanding of the mechanistic links between the vaginal microbiome and PPROM and discusses the clinical implications for future therapeutic strategies. Methods: A comprehensive literature search was conducted in the PubMed, Scopus, and Google Scholar databases. The selection focused on peer-reviewed articles including systematic reviews, meta-analyses, clinical trials, and influential observational studies (e.g., cohort and case-control), as well as key preclinical studies investigating the vaginal microbiome, PPROM pathogenesis, and relevant therapies. Results: The synthesized evidence supports a multi-step mechanistic framework wherein ascending pathobionts, characteristic of dysbiosis, trigger a host inflammatory cascade via Toll-like receptors. This inflammatory milieu orchestrates a synergistic attack on fetal membrane integrity through three primary pathways: (1) enzymatic degradation of the extracellular matrix by matrix metalloproteinases (MMPs), (2) programmed cell death (apoptosis) of membrane cells, and (3) damage from oxidative stress. Although conventional therapies such as antibiotics have limitations, emerging strategies, including probiotics, immunomodulators, and antioxidants, are being developed to target these specific mechanistic pathways. Conclusion: This review positions the vaginal microbiome as a central player in the pathophysiology of PPROM, rather than merely a risk factor. This mechanistic understanding shifts the therapeutic focus from broad-spectrum antibiotics toward targeted therapies designed to prevent dysbiosis or neutralize specific downstream inflammatory and degradative pathways. Translating this knowledge into effective clinical practice through rigorous randomized controlled trials remains a critical priority for improving perinatal outcomes.