From Microbes to Motherhood: Exploring the Link Between the Uterine Microbiome and Fertility
The importance of a healthy uterine microbiome for optimizing fertility outcomes is a new and exciting area in the world of reproductive medicine. We once thought the uterus was a sterile organ, but we now know that it is colonized with bacteria, and recent research has shown that the type of bacteria present in the endometrium influences fertility outcomes. Let’s dive into the research shall we!
Fertility Microbiome Research
According to a clinical trial published in 2016 in the American Journal of Obstetrics and Gynecology, non-lactobacillus dominant endometrium in IVF patients is associated with lower implantation rates, clinical pregnancy rates, and live birth rates, in comparison to lactobacillus dominant endometrium. This suggests that a healthy uterine microbiota is essential for successful implantation and pregnancy (1).
Another study conducted in 2017 also found that a healthy uterine microbiota depends on the nutrients and hormones available to the uterus, as well as the microbiota in the vagina and the peritoneal cavity. Vaginal Lactobacillus spp. is known to inhibit other pathogenic bacteria by maintaining a high concentration of lactic acid and hydrogen peroxide production (2).
A clinical trial published in 2020 showed that the endometrial microbiota can be changed with treatment in RIF (repeated implantation failure) patients undergoing IVF. According to the study, success rates were most significant in the oral antibiotic plus vaginal probiotic treatment group (78.6%) compared to oral prebiotic plus probiotic group (29.5%), oral antibiotic group (33.3%), oral probiotic plus prebiotic and antibiotic (33.3%), and vaginal probiotic group (43.6%). . The study also found that lactobacilli tend to be highest in the luteal phase of the cycle and lowest in the follicular phase (3).
Moreover, a multicenter prospective observational study conducted in 2022 showed that a dysbiotic endometrial microbiota is related to poorer reproductive outcomes in women undergoing IVF, and lactobacillus dominant endometrial microbiota is associated with a significantly higher live birth rate. This study suggested that a dysbiotic endometrial microbiome should be considered for a potential cause of recurrent implantation failure and/or pregnancy loss (4).
In light of these findings, the need to test and treat the endometrial microbiome cannot be overlooked. A first clinical trial conducted in Jan 2023 (prospective cohort study) showed that testing and treating the endometrial microbiome improves reproductive success in women undergoing IVF with a history of RIF. As such, interventions aimed at restoring the endometrial microbiota and promoting a healthy microbiome may play a crucial role in improving fertility outcomes (5).
How can I improve the health of my uterine microbiome?
If you are working with a reproductive endocrinologist, ask them if endometrial microbiome testing would be appropriate for you. In some cases empirical treatment may also be recommended. For instance in naturopathic practice, both oral and vaginal probiotics are often recommended in cases of unexplained infertility, RIF, recurrent pregnancy loss (RPL), or when there is a suspected immunological component at play.
Overall, ongoing research is critical to advancing our understanding of the uterine microbiome and its role in female reproductive health for improved reproductive outcomes.
If you would like to learn more about this topic, please don't hesitate to book in for a naturopathic appointment at Juniper Family Health. We are here to help!
In health and happiness,
Dr. Meghan van Drimmelen, ND | Naturopath Victoria BC
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