The Role of the Physiological Endometrial Microbiota in Assisted Reproduction Outcomes
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- This is an observational study: the protocol does not assign a study treatment.
- Who it may be relevant to
- Registry conditions: Repeated IVF Failure, Microbiota. Basic parameters: 18 years — 54 years · Female.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Greece
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
The goal of this observational study is to investigate the influence and contribution of the normal composition and balance of the endometrial microbiota on the achievement of embryo implantation and the maintenance of pregnancy in women undergoing IVF, with comparable clinical profiles, including patients with a history of RIF or RPL, evaluated under identical treatment protocols and hormonal conditions. The main questions it aims to answer are: 1. Does the normal composition of the endometrial microbiota, particularly the dominance of Lactobacillus species, influence embryo implantation success in women undergoing IVF? 2. Does the endometrial microbiota profile affect pregnancy maintenance, ongoing pregnancies, and live birth rates in women with a history of recurrent implantation failure (RIF) or recurrent pregnancy loss (RPL) Participants will not undergo any additional interventions beyond standard clinical care.They will provide clinical data already collected as part of routine IVF procedures.
Detailed description
Endometrial biopsies were collected from patients using a Pipelle catheter during the designated phase of the menstrual cycle. Each sample was immediately placed in a specialized preservative solution and transported to two external laboratories for analysis.
In the first laboratory, bacterial DNA was extracted using a CE-IVD kit, followed by targeted amplification and barcoded sequencing of seven hypervariable regions (V2, V3, V4, V6, V7, V8, V9) of the 16S rRNA gene using the 16STM metagenomic kit and Ion Torrent sequencing system (Ion GeneStudio S5 with Ion Chef Instrument). Data were analyzed with Ion Reporter™ software and MicroSEC ID, using MicroSEC ID and Greengenes databases for taxonomic classification.
In the second laboratory, total DNA was extracted, and targeted amplification of the 16S rRNA gene was performed using the 16S Barcoding Kit 24 V14 (Nanopore), followed by NGS on the MinION Mk1C analyzer. Bioinformatic analysis was conducted using the EPI2ME Labs 16S workflow. Bacterial composition was classified at the genus level, with results expressed as relative abundance percentages. OTU-level data were not disclosed.
Interpretation of microbiota profiles was performed by the treating physician or clinical geneticist. Patients whose samples showed decreased Lactobacillus abundance or the presence of potentially pathogenic microorganisms received individualized interventions. These interventions included a two-week course of antibiotics tailored to the patient's clinical history, followed by probiotics administered orally or via combined oral and vaginal routes for two weeks to two months. Antifungal agents were administered when clinically indicated.
Embryo transfer schedules were adapted based on microbial profiles and clinical assessment. Patients with normal microbial profiles proceeded with IVF in the next cycle. Patients with abnormal profiles, signs of inflammation, or potential pathogenic colonization had embryo transfer postponed for at least one month following completion of the therapeutic regimen.
The study provides a detailed methodological framework for endometrial microbiota analysis, including sample collection, DNA extraction, sequencing strategies, bioinformatic pipelines, and clinical decision-making based on microbial composition, aiming to support personalized management in assisted reproduction.
Primary outcome measures
- Implantation Rate according to microbiome profile [Time frame: From the day of the embryo transfer to the day of confirmation of implantation (2-4 weeks)]
- Ongoing Pregnancy/Live Birth Rate according to microbiome profile [Time frame: From the day of embryo transfer up to the end of the first trimester (up to 12 weeks of gestation) and live birth until delivery (up to 40 weeks of gestation)]
- Biochemical pregnancy rate and microbiome status [Time frame: From the day of embryo transfer to the day of confirmation of implantation (2-4 weeks)]
Secondary outcome measures (1)
- Endometrial microbiota composition [Time frame: At time of biopsy collection (during procedure)]
Eligibility criteria
Inclusion criteria
- Individuals who are biologically female.
- Age between 18 and 54 years, in accordance with the legally permitted age limits for embryo transfer in Greece.
- Undergoing in vitro fertilization (IVF) treatment.
- Clinical history consistent with recurrent implantation failure (RIF) or recurrent pregnancy loss (RPL) and comparable IVF treatment profiles.
- Ability to provide informed consent for the use of clinical and microbiome data for research purposes
Exclusion criteria
- Individuals who are not biologically female.
- Age below 18 or above 54 years.
- Absence of endometrial biopsy samples or incomplete clinical data.
- Presence of significant uterine abnormalities or medical conditions that contraindicate embryo transfer.
- Participation in another interventional clinical study that may interfere with microbiome assessment or IVF outcomes.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Observational model
- Cohort
Study locations
Greece · 1 center
- Assisting Nature — Thessaloniki
Identifiers
NCT: NCT07606053 · Microbiome-AN011 · Assisting Nature