Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder affecting up to 20% of women of reproductive age worldwide. Characterized by symptoms such as irregular menstrual cycles, excess androgen levels, and polycystic ovaries, PCOS is a leading cause of infertility. Beyond these reproductive concerns, the syndrome is accompanied by systemic risks, including metabolic disturbances and increased susceptibility to gestational complications such as miscarriage, gestational diabetes, and preterm birth. While fertility treatments can assist women with PCOS in achieving pregnancy, they do not eliminate the heightened risks associated with pregnancy outcomes.
Scientific and Clinical Evidence: What the Data Tell Us
Recent research presented at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) has shed light on the microbiota and metabolic factors influencing these risks. In a study involving 220 women under the age of 35, researchers compared gut microbiota and serum metabolomic profiles between 110 PCOS patients and 110 matched controls. The findings were striking, revealing distinct differences in gut microbial diversity and metabolic markers linked to pregnancy outcomes.
One of the key observations was a reduction in the gut bacterium Parabacteroides merdae (P. merdae) among women with PCOS. P. merdae is associated with metabolic health, and its decreased presence correlated with poorer endometrial function. Additionally, women with PCOS exhibited higher levels of branched-chain amino acids (BCAAs), particularly isoleucine, in both serum and endometrial tissues. BCAAs are known to play a role in cellular aging and metabolic dysfunction. Laboratory studies further demonstrated that exposure of endometrial cells to isoleucine promoted cellular senescence, impairing the cells’ ability to support pregnancy.
Increased Pregnancy Risks and Early Uterine Aging
The study highlighted a nearly twofold increase in the risk of adverse pregnancy outcomes among women with PCOS compared to those without the condition. These outcomes ranged from miscarriage and preterm birth to perinatal death and gestational diabetes. The elevated isoleucine levels and reduced microbial diversity were found to induce premature aging-like changes in the uterus, even in women under 35 years old. This premature “endometrial aging” may underlie the high miscarriage rates observed in women with PCOS, as it compromises the uterus’s receptivity to implantation and its ability to sustain a pregnancy.
Correct Health Practices and Practical Recommendations
These findings highlight the need for tailored interventions aimed at restoring microbial and metabolic balance in women with PCOS. Potential strategies include dietary modifications to reduce BCAA intake, the use of probiotics to enhance beneficial gut bacteria like P. merdae, and personalized medical care to manage metabolic dysfunction. Further research is needed to evaluate the efficacy of these interventions in improving pregnancy outcomes in women with PCOS.
Expert Insights and Commentary
Dr. Aixia Liu, the lead author of the study, emphasizes the significance of these findings for clinical practice: “Even younger women with PCOS face unexpectedly high rates of miscarriage and other complications despite achieving pregnancy. This research underscores the importance of addressing systemic metabolic and microbial imbalances, not just the reproductive symptoms.” Dr. Anis Feki, Chair-Elect of ESHRE, adds: “The study provides compelling evidence that metabolic and microbial imbalances in PCOS directly impair endometrial receptivity. Future research should explore the potential of microbiota-targeted therapies to enhance reproductive outcomes.”
Conclusion
The study offers a groundbreaking perspective on the systemic impacts of PCOS, linking gut microbiota and metabolic markers with pregnancy complications. These findings pave the way for innovative approaches to treating PCOS, emphasizing the role of personalized care and microbiota health. As researchers continue to explore these connections, women with PCOS may benefit from a deeper understanding of their condition and access to therapies tailored to their unique needs.
References
- Gut bacteria and amino acid imbalance linked to higher miscarriage risk in women with PCOS. European Society of Human Reproduction and Embryology. June 29, 2025. Accessed July 2, 2025. https://www.eurekalert.org/news-releases/1088637.
- Azziz R, Carmina E, Chen Z, et al. Polycystic ovary syndrome. Nature Reviews Disease Primers. 2016. doi:10.1038/nrdp.2016.57
