There is growing emphasis on the potential significance of the placental microbiome and microbiome–metabolite interactions in immune responses and subsequent pregnancy outcome, especially in relation to preterm birth (PTB). This review discusses in detail the pathomechanisms of placental inflammatory responses and the resultant maternal–fetal allograft rejection in both microbial-induced and sterile conditions. It also highlights some potential placental-associated predictive markers of PTB for future investigation. The existence of a placental microbiome remains debatable. Therefore, an overview of our current understanding of the state and role of the placental microbiome (if it exists) and metabolome in human pregnancy is also provided. We critical evaluate the evidence for a placental microbiome, discuss its functional capacity through the elaborated metabolic products and also describe the consequent and more established fetomaternal inflammatory responses that stimulate the pathway to preterm premature rupture of membranes, preterm labour and spontaneous PTB.
- microbial pathogenic
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Handling editor Tony Mazzulli.
Presented at A portion of this work was presented at the Sheffield Global Health Symposium as a short oral presentation in January 2020.
Contributors The review idea was conceptualised by all authors. EA and KMP performed the literature search and produced the initial draft. All authors contributed to the subsequent drafts and critical revision of the manuscript with KMP and EA leading the process. All authors read and approved the final draft before submission for publication.
Funding This review was supported by funding from the National Institute for Health Research (NIHR, 17/63/26).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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