Infertility and the microbiota.

Microbiota exist in the vagina, uterus, cervix, and male testes and play a vital role in maintaining a normal pregnancy.

• Over the past decade, intensive research on reproductive tract microbiota has led to identification of these microbial communities.
• The review identifies these sites as key locations where microbiota influence reproductive outcomes.
• Dysbiosis at these sites has been linked to infertility.

Dysbiosis of gut microbiota has been linked to infertility.

• The gut microbiota represents an additional non-reproductive tract site where microbial imbalance contributes to infertility.
• The review discusses gut microbiota dysbiosis alongside reproductive tract dysbiosis as parallel mechanisms.
• This association extends the role of microbiota in reproductive health beyond the reproductive tract itself.

Multiple mechanisms by which microbiota dysbiosis triggers infertility were identified, including dysbiosis of bacterial ecological ratios, microbiota-mediated immune system imbalance, inflammatory responses, and effects on signaling pathways.

• The review focuses specifically on four mechanistic categories: bacterial ecological ratio dysbiosis, immune imbalance, inflammatory responses, and signaling pathway effects.
• These mechanisms apply to both reproductive tract and gut microbiota contexts.
• The mechanistic framework provides a basis for understanding how microbial community changes translate to reproductive dysfunction.

Gender-specific microbiota demonstrate significant capacity for diagnosis, prognosis, and treatment of infertility-associated reproductive disorders.

• The review discusses gender-specific microbiota profiles separately for their clinical utility.
• Applications span diagnostic, prognostic, and therapeutic dimensions of reproductive medicine.
• This finding supports the use of microbiota profiling as a clinical tool in fertility assessment.

Therapeutic strategies targeting the microbiota were identified as potential approaches to prevent or treat infertility.

• The review extensively analyzes microbiota-targeting therapeutic strategies.
• These strategies are presented as laying the foundation for future customized precision medicine.
• Therapeutic targeting encompasses both prevention and treatment of infertility.
• The analysis covers both male and female infertility contexts given the gender-specific microbiota discussion.