Short answer: The bacteria in the vagina are part of the vaginal environment. Research has linked certain bacterial patterns to IVF outcomes, but this does not prove that lactic acid bacteria supplements increase the chances of becoming pregnant. Any concerns need to be assessed based on symptoms, not solely on a microbiome test.
The vaginal bacterial flora
Lactic acid bacteria are common in the vagina and help maintain an acidic environment. The bacterial flora varies between individuals and over time. Therefore, a single bacterial finding should not be used on its own to determine whether the vaginal environment is healthy or to explain infertility.
The link to fertility
Studies have found that a flora dominated by lactobacilli—particularly the species Lactobacillus crispatus—is associated with higher rates of pregnancy and live births after embryo transfer in IVF. Conversely, dysbiosis has been linked to repeated implantation failure. However, these associations are complex, and research is still in its early stages.
What can you do?
Seek medical advice for issues such as recurrent changes in vaginal discharge or other concerns. ESHRE does not recommend routine profiling of the vaginal or uterine microbiome in cases of repeated implantation failure. Such tests and supplements should not replace established investigations.
General information, not medical advice. Contact a healthcare professional if you have any concerns.
The vaginal bacterial flora is not the same as the gut flora. Findings from studies of one environment cannot automatically be applied to the other.
Sources
- The Role of the Genital Tract Microbiome in Human Fertility: A Literature Review (2025). Journal of Clinical Medicine.
- ESHRE: recommendations for repeated implantation failure, 2023