Impact of vaginal microecological differences on pregnancy outcomes and endometrial microbiota in frozen embryo transfer cycles
Open accessAbstract
Purpose This prospective study investigates the correlation between vaginal microecology and pregnancy outcomes and explores their impact on endometrial microbiota composition during frozen embryo transfer (FET) cycles. Additionally, the impact of transvaginal Lactobacillus supplementation on reproductive outcomes in patients with previous failed cycles was assessed.Methods A total of 379 patients undergoing FET at a reproductive medicine center were categorized into clinical pregnancy (CP), miscarriage (MISC), and non-pregnant (NP) groups. Vaginal specimens were collected for microecological evaluation prior to embryo transfer. Endometrial microbiota samples were obtained during embryo transfer for 16S rRNA gene sequencing analysis to assess endometrial microbiota composition. Vaginal microecological indicators, including pH, Lactobacillus dominance, and leukocyte esterase activity, were measured. Transvaginal Lactobacillus supplementation was investigated in 60 patients with previous failed cycles.Results Vaginal microecology significantly correlated with pregnancy outcomes, with normal microecology associated with a higher clinical pregnancy rate. Vaginal pH and leukocyte esterase activity were significantly associated with clinical pregnancy. Furthermore, vaginal microecological differences significantly impacted endometrial microbiota composition. However, no significant differences were observed in endometrial microbiota composition among the CP, MISC, and NP groups. Notably, transvaginal Lactobacillus supplementation increased the clinical pregnancy rate without affecting the miscarriage rate.Conclusion This study highlights that normal vaginal microecology, characterized by lower pH and leukocyte esterase negativity, is associated with a higher likelihood of clinical pregnancy following FET. Importantly, vaginal microecological differences influence endometrial microbiota composition. Moreover, transvaginal Lactobacillus supplementation appears promising in improving clinical pregnancy rates in patients with previous failed cycles. These findings contribute to a better understanding of the interplay between vaginal and endometrial microbiota and offer potential interventions to enhance reproductive success in assisted reproductive technologies.
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Wei and Gilboa had high risk of bias, with no detailed information on concealment and randomization methods.
“Wei [25] and Gilboa [20] encountered a high risk of bias, with no detailed information on concealment and randomization methods.”
From Vaginal probiotics as therapeutic adjuncts for improving embryo transfer success rates: a systematic review and meta-analysis (2025) · cites this paper as [25]
The Patient population section says 60 patients were “randomly assigned to control and treatment groups” but gives no details of the randomization method or allocation concealment. The paper does not assess its own risk of bias, so it does not support the attributed high-risk judgment. This verdict concerns Wei only; Gilboa is a separate citation. (LLM, conf=0.78)
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References 31 · Cited by 16
- Authors
- Wei, Q., Chen, H., Zou, H., Zhang, H., Liu, S., Zheng, J., Zhang, S., & Hu, L.
- Affiliations
- Second Affiliated Hospital of Chongqing Medical University (CN)
- Corresponding author
- Zhang, Shen
- Hu, Lina
- Venue
- Journal of Assisted Reproduction and Genetics
- Published
- 2024-02-22
- Volume
- 41
- Issue
- 4
- Pages
- 929-938
- ISSN
- 0740-7769 (ISSN-L)
- 1058-0468
- 1573-7330
- PMC
- PMC11052970
- OpenAlex
- W4392078455
- Cited by
- 16
- References
- 31
- Citations by year
- 2026: 10 · 2025: 4 · 2024: 2
- FWCI
- 4.17
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Licence
- Locations
- Journal of Assisted Reproduction and Genetics (publishedVersion)
- PubMed Central (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Natural Science Foundation of China (82101710)
- Science-Health Joint Medical Scientific Research Project of Chongqing (2022QNXM023)
- Natural Science Foundation of Chongqing (cstc2021jcyj-msxmX0097)
- Strategic Collaborative Research Program of the Ferring Institute of Reproductive Medicine, Ferring Pharmaceuticals and Chinese Academy of Sciences (FIRMD200502)
- Topics
- Life Sciences › Immunology and Microbiology › Microbiology › Reproductive tract infections research
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gut microbiota and health
- Life Sciences › Immunology and Microbiology › Immunology › Reproductive System and Pregnancy
- Keywords
- vaginal microbiota, endometrial microbiota, frozen embryo transfer, pregnancy outcomes, miscarriage, vaginal pH, leukocyte esterase, clinical pregnancy rate, assisted reproduction
- MeSH terms
- Abortion, Spontaneous, Adult, Embryo Transfer, Endometrium, Female, Fertilization in Vitro, Humans, Lactobacillus, Pregnancy, Pregnancy Outcome, Prospective Studies, Vagina, Cryopreservation, Pregnancy Rate, Microbiota
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