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How Microbiome determines the Success of IVF

The female genital tract microbiome plays a crucial role in the success of in vitro fertilization (IVF) treatments. Several studies have found associations between the composition of the vaginal microbiome and IVF outcomes:


Photo: AI fantasy world of bacteria


Microbiome diversity and composition: Studies have shown that the vaginal microbiome of women undergoing IVF tends to be more diverse and less dominated by Lactobacillus species compared to women who conceive naturally.[2][3] This dysbiotic vaginal microbiome has been linked to lower implantation rates and higher risk of preterm birth in IVF pregnancies.[2]

 

Specific bacterial taxa: The presence of certain bacterial taxa, such as Enterobacteriaceae and Staphylococcus, has been associated with lower pregnancy rates in IVF patients.[3] In contrast, a Lactobacillus-dominant vaginal microbiome is associated with better reproductive outcomes.[1]

 

Mechanisms: The vaginal microbiome can influence IVF success through several mechanisms. Dysbiosis can lead to inflammation, oxidative stress, and impaired endometrial receptivity, all of which can negatively impact embryo implantation and pregnancy.[1][4][5] The microbiome may also interact with the host immune system to modulate fertility.[5]

 

Clinical implications: Given the importance of the reproductive microbiome, there is growing interest in using microbiome profiling to predict IVF success rates and guide clinical management.[4] Strategies to modulate the microbiome, such as the use of probiotics, may also hold promise for improving IVF outcomes.[1][3]


Which bacterial species are most beneficial for IVF success


Women with a Lactobacillus-dominated vaginal microbiome (>90% Lactobacillus) had significantly higher median percentages of endometrial Lactobacilli compared to those with a non-Lactobacillus-dominated microbiome[9].

A Lactobacillus-dominant vaginal microbiome, particularly with high levels of Lactobacillus crispatus, is associated with higher pregnancy rates in IVF patients.[6][7][8]


In contrast, the presence of certain bacterial taxa such as Gardnerella vaginalis, Staphylococcaceae, and Enterobacteriaceae has been linked to lower implantation rates and poorer IVF outcomes. [6][7][8] Only 6% of the women affected by the previous conditions became pregnant after an embryo transfer. [9]


The study in IVF clinicls of 50 couples, demonstrates that IVF does not occur in a sterile environment either (the study determined the prevalence and counts of bacteria in IVF samples, according scientist probably from semen). [10] Apparently, just antibiotic treatment and eliminating all bacteria, does not help, there is an important need to recover the healthy bacterial dominance in both partners.


In summary, maintaining a healthy, Lactobacillus-dominant vaginal microbiome, particularly with high levels of Lactobacillus crispatus, appears to be crucial for optimizing pregnancy outcomes in IVF patients. Avoiding dysbiosis and the overgrowth of non-Lactobacillus species is important for IVF success.


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