Characterization of the Vaginal Microbiome in Women with Infertility and Its Potential Correlation with Hormone Stimulation during In Vitro Fertilization Surgery Original paper

What was studied?

This study, Characterization of the Vaginal Microbiome in Women with Infertility and Its Potential Correlation with Hormone Stimulation during In Vitro Fertilization Surgery, investigated vaginal microbiome signatures in women with secondary infertility, comparing them with healthy women and examining whether ovulation-inducing hormone stimulation during IVF alters these microbial communities. The goal was to identify microbial shifts—particularly deviations from microbiome patterns dominated by Lactobacillus—that might contribute to infertility or IVF outcomes.

Who was studied?

Researchers analyzed vaginal swabs from 30 women with secondary infertility undergoing IVF and 92 healthy women aged 23–42. Samples were collected during distinct hormonal phases: follicular and ovulatory stages for healthy women, and before and after GnRH agonist plus recombinant hCG stimulation for infertility patients. The study, therefore, captured microbial variation across natural and pharmacologically induced hormonal contexts.

Most important findings

Infertile women exhibited reduced vaginal microbiome diversity and richness, especially during the follicular phase. Their communities showed lower Lactobacillus and Leuconostoc abundance, paired with higher levels of Atopobium, Aerococcus, and Bifidobacterium. LEfSe analysis identified 17 taxa discriminating between infertile from healthy women, including Megasphaera, Pseudomonas, and Veillonella. These shifts moved the vaginal ecosystem toward anaerobic, BV-associated microbiota. Healthy women displayed pronounced microbial fluctuations during ovulation, including increased Cyanobacteria, Bifidobacterium, and Prevotella. Importantly, infertile women did not exhibit significant microbiome changes after hormonal stimulation during IVF, suggesting hormone-insensitive microbial communities. Correlation analyses showed strong positive associations among BV-linked anaerobes and negative associations between Firmicutes (largely Lactobacillus) and Bifidobacterium/Bacteroidetes.

Key implications

A pattern emerges in which secondary infertility aligns with a Lactobacillus-depleted, anaerobe-enriched vaginal microbiome, resembling BV-like signatures. Such communities may impair mucosal immunity, increase pH, and favor pathogen overgrowth, compromising embryo implantation potential. The lack of microbiome responsiveness to ovulation-inducing hormones suggests a dysbiotic community that is less adaptable to hormonal modulation, potentially underlying reduced reproductive success. This study highlights microbial biomarkers—Atopobium, Prevotella, Megasphaera, Aerococcus, and Bifidobacterium—that may be clinically relevant for diagnostic microbiome profiling and microbiome-targeted fertility interventions.

Citation

Zhao C, Wei Z, Yang J, Zhang J, Yu C, Yang A, Zhang M, Zhang L, Wang Y, Mu X, Heng X, Yang H, Gai Z, Wang X, Zhang L. Characterization of the vaginal microbiome in women with infertility and its potential correlation with hormone stimulation during in vitro fertilization surgery. mSystems. 2020;5(4):e00450-20. doi:10.1128/mSystems.00450-20