Microbiota and Human Reproduction: The Case of Female Infertility Original paper

What was reviewed?

This review comprehensively examined current research on the microbiota of the female reproductive system, focusing specifically on its role in infertility and reproductive health. It analyzed literature investigating both the lower reproductive tract (vaginal microbiota) and the upper reproductive tract (uterus, fallopian tubes, and ovaries). The authors reviewed the microbial composition of these regions, highlighting the dominance of Lactobacillus species under normal conditions, and explored how deviations from this balanced microbial community—referred to as dysbiosis—might affect fertility outcomes and influence the success rates of assisted reproductive technologies (ART), particularly in vitro fertilization (IVF).

Who was reviewed?

The review summarized studies involving women across various reproductive statuses, including fertile women, infertile women, and women undergoing ART procedures. Literature assessing microbial differences between fertile and infertile groups, particularly in terms of vaginal and uterine microbiota composition, formed the basis of the review. The authors also incorporated evidence related to microbiome shifts associated with different life stages, hormone fluctuations, lifestyle influences, and environmental exposures, providing clinicians with an extensive view of factors affecting reproductive microbiota dynamics.

What were the most important findings?

The central findings of the review emphasized the critical role of Lactobacillus species in maintaining reproductive health through their dominance in the reproductive tract, particularly in the vagina. Lactobacilli were identified as crucial for creating an acidic environment that inhibits pathogen growth. Dysbiosis, characterized by reduced Lactobacillus abundance and increased prevalence of anaerobic bacteria like Gardnerella vaginalis, Atopobium vaginae, and Ureaplasma spp., was strongly linked to infertility, chronic inflammatory conditions, and notably poorer outcomes in IVF treatments, including lower implantation rates and increased pregnancy complications. The review highlighted a significant continuity of bacterial communities along the reproductive tract, suggesting a microbiological link from the lower to upper regions. Moreover, the potential influence of male partner semen microbiota on female reproductive health was underscored, suggesting that fertility evaluations should also consider the microbiome of the male partner.

What are the greatest implications of this review?

The review’s greatest clinical implication is that clinicians should consider reproductive microbiota assessment as an integral part of fertility evaluations and infertility treatment strategies. Understanding the link between microbiota and infertility provides an opportunity to enhance reproductive outcomes by diagnosing and correcting microbial dysbiosis through targeted probiotics, lifestyle interventions, and possibly tailored antibiotic treatments. This approach could substantially improve IVF success rates and overall fertility management. Moreover, the identification of microbial signatures associated with fertility may facilitate personalized reproductive healthcare strategies, optimizing conditions not just for conception but also for the long-term reproductive health of couples and their offspring.