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  • Writer's pictureDr. H. Singh, ND

How Probiotics might Improve IVF Success Rates

Updated: Jun 2, 2021

When I first started reading in to the research around the reproductive microbiome and gut microbiomes impacting IVF success rates, one of the first questions that popped in to my head was: how does an oral probiotic impact the bacteria in the uterus? They are both, after all, two different separate organs. What is it that connects the two organs and allows them to "communicate" and affect the growth of different bacteria in the other?

Newer research over the years has established two different methods of communication: the microgenderome and the immune system response.

The microgenderome refers to the change in hormone levels influenced by the microbiome. For example, in certain animal studies, it has been shown that reducing the amount of bacteria in the gut can decrease testosterone levels in males and increase testosterone levels in females. The type of bacteria present in the gut also impact the levels of estrogen in the blood. Gut dysbiosis (imbalance in the gut bacterial balance) has been shown to increase levels of circulating estrogen in the blood, and may play a role in worsening reproductive conditions, such as, endometriosis.

Fluctuating levels of estrogen in the blood, as a result of perimenopause/menopause can also reduce the growth of lactobacillus spp. (which help to protect the vaginal canal from infections), reduce the acidity of the vaginal secretions and predispose the local environment to infection.

Changes to either the gut microbiome or the reproductive microbiome alters the production of inflammatory markers and can increase the levels of inflammation in the other organ. The increase in inflammation usually leads to an increased predisposition for infection.

Taking oral probiotics have been shown to influence the bacterial population in the reproductive tract as well. Taking L. Rhamnosus as an oral probiotic seemed to increase its concentration in the reproductive microbiome by about 10%. But how does this impact IVF success rates?

The presence of a lactobacillus dominant microbiome has been shown to more than double the chances of a positive pregnancy with IVF compared to patients with a non-lactobacillus dominant reproductive microbiome. It has been observed to also increase the chances of carrying to term with a live birth by up to 10x when compared to the non-lactobacillus dominant group.

For natural cycles, the presence of various strains of lactobacillus spp. in the vaginal canal have been show to protect sperm motility and viability, potentially improving the quality of the sperm cells and their health prior to reaching/fertilizing a follicle.


  1. Quaranta, G., Sanguinetti, M., & Masucci, L. (2019). Fecal Microbiota Transplantation: A Potential Tool for Treatment of Human Female Reproductive Tract Diseases. Frontiers in Immunology, 10.

This article is in no way a replacement for medical advice or medical care, it is advised that anyone concerned about their Health should speak with their Naturopathic Doctor. Please discuss with your healtcare provider and only make changes to your medications regimen if recommended by your doctor and under their guidance.

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