Exploring the promising role of Ligilactobacillus salivarius PS11610 in improving IVF outcomes through microbiome modulation
For the millions of couples worldwide struggling with infertility, the journey toward parenthood can feel like an uphill battle against unseen forces.
In vitro fertilization (IVF) has offered hope to many, but with success rates that remain modest—typically 30-35% per cycle—scientists continue searching for ways to improve these odds 1 . Recently, researchers have turned their attention to an unexpected ally in this struggle: the human microbiome.
Enter Ligilactobacillus salivarius PS11610, a specialized bacterial strain showing remarkable potential in enhancing fertility outcomes. Groundbreaking research suggests this probiotic could play a pivotal role in shifting the delicate balance toward successful pregnancy, offering new hope to those on the challenging path of assisted reproduction 1 2 .
A specialized probiotic strain may improve IVF outcomes by modulating the reproductive microbiome.
When we think of microbiomes, we typically picture gut bacteria, but our bodies host complex microbial communities in various locations, including the reproductive system. A healthy female urogenital microbiome is characterized by low bacterial diversity with Lactobacillus species dominating (>90%) 2 . These beneficial bacteria protect against pathogens by producing lactic acid (lowering vaginal pH), blocking adhesion sites on epithelial cells, and producing antimicrobial substances like bacteriocins and hydrogen peroxide 2 .
The opposite of this healthy state is dysbiosis—a microbial imbalance. The most common urogenital dysbiosis is bacterial vaginosis, where protective lactobacilli are replaced by pro-inflammatory microorganisms like Gardnerella vaginalis, Atopobium vaginae, and Prevotella species 2 . This condition affects approximately 40% of women undergoing assisted reproductive treatment and has been linked to poorer pregnancy outcomes 2 .
Interestingly, the microbiome's influence extends beyond female fertility. The male seminal microbiota also plays a crucial role in couple health and pregnancy outcomes, with alterations in these microbial communities potentially affecting semen quality 2 6 .
In a preliminary retrospective analysis conducted at a fertility clinic in Lisbon, Portugal, researchers investigated the impact of Ligilactobacillus salivarius PS11610 on IVF outcomes 1 2 . The study followed 694 women aged 18-49 during their first IVF treatment over two one-year periods:
September 2021 - August 2022
No probiotic supplementation
September 2022 - August 2023
Daily supplementation with L. salivarius PS11610
The participants in the intervention group took one capsule containing 1 × 10^9 CFU of L. salivarius PS11610 every 12 hours for at least one month before their IVF procedures 2 . Researchers then compared outcomes across different types of IVF cycles: those without embryo transfer, those with fresh embryo transfer, and frozen embryo transfer (FET) cycles.
The results revealed fascinating patterns that varied across different types of IVF procedures:
In cycles where embryos were created but not immediately transferred, the study found no significant differences in most parameters between the probiotic and control groups. Surprisingly, embryo quality (specifically categories 2 and 3) was actually higher in the group without PS11610 supplementation 1 2 .
Similar to cycles without transfer, the fresh embryo transfer group showed higher embryo quality in categories 2 and 3 in the control group compared to the probiotic group 2 .
The most promising results emerged in the frozen embryo transfer (FET) group, where the probiotic supplementation demonstrated significant benefits.
| Outcome Measure | With L. salivarius PS11610 | Without L. salivarius PS11610 | Statistical Significance |
|---|---|---|---|
| Live Birth Rate | 26.4% | 17.9% | p = 0.034 |
| Biochemical Pregnancy Rate | 42.6% | 34.0% | p = 0.071 |
These findings suggest that while L. salivarius PS11610 might not improve initial embryo quality metrics, it appears to create a more receptive environment for implantation and development once embryos are transferred to the uterus, particularly in frozen cycles 1 2 .
| Research Material | Function in the Study |
|---|---|
| Ligilactobacillus salivarius PS11610 | The investigational probiotic strain with documented antimicrobial activity against pathogens associated with reproductive dysbiosis |
| Fertibiome® | The specific probiotic formulation containing PS11610 used in the clinical study |
| Culture Media | Specialized nutrient solutions used to support the growth of embryos in the laboratory setting |
| Hormone Assays | Blood tests to measure hormone levels and monitor ovarian response during stimulation |
| Transvaginal Ultrasound | Imaging technology used to monitor follicular development and guide egg retrieval |
| Embryo Grading System | Standardized classification (Istanbul Consensus) to assess embryo quality before transfer |
The PS11610 study represents a promising development in the growing field of microbiome-based fertility interventions. While the exact mechanisms behind its benefits require further investigation, researchers speculate that the probiotic may improve the uterine environment by:
Associated with dysbiosis through antimicrobial activity 1
In the reproductive tract 4
To facilitate embryo implantation 2
This approach aligns with other research on probiotic interventions for fertility. For instance, a separate randomized controlled trial using a different strain, Ligilactobacillus salivarius CECT5713, found that it significantly increased pregnancy success rates (48.1% vs. 20.0% in the placebo group) in couples with unexplained infertility 4 .
While these preliminary findings are exciting, researchers caution that larger, prospective studies are needed to confirm these results and optimize protocols for probiotic supplementation in fertility treatments 1 2 . Important questions remain about ideal dosing, timing, and which patient populations might benefit most.
| Strain | Study Type | Key Findings |
|---|---|---|
| L. salivarius PS11610 | Retrospective analysis | Significant increase in live birth rates in frozen embryo transfer cycles |
| L. salivarius CECT5713 | Randomized, triple-blind, placebo-controlled trial | Significantly higher pregnancy success rates (48.1% vs. 20.0%) in couples with unexplained infertility |
The exploration of Ligilactobacillus salivarius PS11610 as a potential adjunct to IVF represents a fascinating convergence of microbiome science and reproductive medicine. While not a magic bullet, this research highlights the importance of considering the microbial environment alongside traditional fertility treatments.
As science continues to unravel the complex interactions between our microbiomes and reproductive health, the prospect of harnessing beneficial bacteria to improve IVF outcomes offers a compelling vision for the future of fertility treatment—one where we work in harmony with the invisible world within us to create new life.