Investigating the Microbiota of Ovarian Follicular Fluid and Vaginal Secretions in Infertile Women with Polycystic Ovary Syndrome: A Prospective Cohort Study

Abstract

Background: Polycystic ovary syndrome (PCOS) is a complex endocrine disorder that affects a significant proportion of women during their reproductive years. It is characterized by hormonal and metabolic dysregulation. Growing evidence suggests that the microbiota present in ovarian follicular fluid and vaginal secretions may significantly influence reproductive outcomes. Objectives: The primary objective of this study is to investigate and compare the microbiota of ovarian follicular fluid and vaginal secretions in infertile women with PCOS, specifically to analyze compositional differences between patients who achieve clinical pregnancy and those who do not. Methods: In this prospective cohort study, follicular fluid and vaginal swabs were collected from 30 women with PCOS enrolled for intracytoplasmic sperm injection (ICSI) cycle at Mahdiyeh Hospital, Tehran, between September 2023 and August 2024. None of the patients had taken metformin or antibiotics for 3 months prior to oocyte retrieval. Quantitative real-time polymerase chain reaction (RT-PCR) was employed to assess the Lactobacillus group, Bifidobacterium spp., Streptococcus spp., Staphylococcus spp., Gardnerella vaginalis, Mycoplasma hominis, Escherichia coli, Bacteroides group, and Prevotella spp. Also, the number and maturity of eggs, fertilization and cleavage rates, number and quality of transferred embryos, male partner's semen parameters, infertility duration, cause and type of infertility, and transfer cycle details were recorded. GraphPad Prism 10 software was used for statistical analysis of the data. Results: While most bacterial profiles showed no significant differences between pregnant and non-pregnant groups, M. hominis levels in left follicular fluid were significantly higher in the non-pregnant group (P-value: 0.0225). There was no statistically significant difference in the number and maturity of eggs, fertilization and cleavage rates, the number and quality of transferred embryos, male partner's semen parameters, infertility duration, cause and type of infertility, and type of embryo transfer cycle between study groups. Conclusions: This study compared the reproductive microbiota in women with PCOS undergoing ICSI cycles and found significantly higher levels of M. hominis in left-ovary follicular fluid in non-pregnant women. Other bacterial and clinical parameters showed no significant differences. Future larger-scale studies using metagenomic sequencing are warranted to confirm this association and further characterize the follicular microenvironment's role in in vitro fertilization (IVF)/ICSI outcomes.