Reproductive tract and follicular fluid microbiota and probiotic interventions in IVF/ICSI outcomes: a systematic review.

Authors

Guangyu Ma, Rujun Zeng, Rui Cai, Bixi He, Jinbiao Han, Rui Gao, Lang Qin

Published in

BMC pregnancy and childbirth. Jul 04, 2026. Epub Jul 04, 2026.

Abstract

To investigate the associations of reproductive tract and follicular fluid microbiota composition, microbial diversity, and probiotic interventions with pregnancy outcomes after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).
PubMed, Embase, Web of Science, and the Cochrane Library were searched from January 2000 to August 2025, with manual screening of reference lists. Original human studies on women undergoing IVF/ICSI reporting reproductive tract or follicular fluid microbiota, pregnancy outcomes, or probiotic interventions were included, encompassing randomized controlled trials and observational studies. Two reviewers independently screened studies, extracted data, and assessed quality using RoB 2.0, ROBINS-I, and JBI tools. Due to heterogeneity in study designs, sampling sites, and microbiota methods, a qualitative synthesis was performed.
Among 2546 identified records, 40 studies met the inclusion criteria. Most studies consistently reported that a Lactobacillus-dominant reproductive tract microbiota, particularly Lactobacillus crispatus, was associated with higher implantation, clinical pregnancy, and live birth rates, whereas non-Lactobacillus or pathogen-enriched microbiota profiles were linked to poorer reproductive outcomes. Microbial diversity alone showed inconsistent associations with IVF/ICSI outcomes. Evidence regarding the influence of follicular fluid microbiota on pregnancy outcomes remains limited. Longer-term or individualized probiotic regimens appeared to increase Lactobacillus abundance and were associated with improved reproductive outcomes, whereas short-term interventions demonstrated minimal benefit.
Species-level and site-specific reproductive tract microbiota profiles appear to better predict assisted reproductive technology outcomes than diversity measures alone. Personalized or longer-duration probiotic strategies may hold therapeutic potential; however, current evidence remains limited and heterogeneous. Well-designed longitudinal and site-specific trials are required to clarify the effectiveness of microbiota-targeted interventions in IVF/ICSI.

PMID:
42401851
Bibliographic data and abstract were imported from PubMed on 05 Jul 2026.

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