Instituto Bernabeu carries out research into the differences in the vaginal microbiome of patients who have been diagnosed with embryo implantation failure

August, 26th 2020

Instituto Bernabeu has carried out research work that analyses if the vaginal and endometrial microbiome is different in patients who have been diagnosed with recurrent implantation failure (with an uncertain reproduction prognosis). The clinic compared them with women who undergo assisted reproduction treatment but who do not have a diagnosis of this kind.

The premise for the research was that embryo implantation is one of the critical steps for successful assisted reproduction treatment. In addition, the vaginal and/or endometrial microbiome plays a very important role in achieving a pregnancy.

The research work, which was managed by Dr Andrea Bernabeu, has been submitted to the 2020 European Society of Human Reproduction and Embryology (ESHRE) congress. This is the leading congress in Europe.

The study involved taking 264 vaginal and endometrial samples from 48 patients. The samples were taken over different stages of the menstrual cycle. The next-generation sequencing technique was used in order to carry out a vaginal microbiome analysis. A single, chromosomally-normal embryo was transferred to patients with a normal endometrial response in ultrasound scans.

The results showed different patterns in the vaginal and endometrial microbiome between the two groups of women. The results were lower in patients in the control group (patients with no recurrent implantation failure). Dr Bernabeu highlights that “a lack of vigour in microbiome patterns in patients with recurrent implantation failure was observed. This could explain their poorer ability to adapt to physiological changes in the endometrium.”


On the other hand, similar results were obtained in different samples taken at different times during the menstrual cycle. This meant that the researchers could determine that microbiome samples can be taken at any time during the cycle. This discovery favours organisation of courses of treatment since it means that embryo transfer does not have to be delayed.

The study concludes that, further to analysis of the results of embryo transfer treatments, patients with a higher percentage of Lactobacillus spp had better pregnancy rates.


The pattern of vaginal/endometrial microbiome as a predictor for outcome of in vitro fertilization (IVF) in patients with or without repetitive implantation failure: a pilot study

A. Bernabeu, B. Lledó, M. C. Díaz, F. Lozano, A. Rodríguez-Arnedo, R. Morales, R. Bernabeu

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