The Role of Vaginal Probiotics in Assisted Reproductive Techniques

The Role of Vaginal Probiotics in Assisted Reproductive Techniques

Infertility is a significant global health concern, affecting approximately 1 in 6 couples. With advances in assisted reproductive techniques (ART), particularly in embryo transfer (ET), there remain challenges in achieving successful pregnancies, especially in women with a history of recurrent implantation failure (RIF). Recent research indicates that the vaginal microbiome plays a crucial role in reproductive success, influencing implantation rates and overall pregnancy outcomes. Probiotics, particularly those containing Lactobacillus strains, have gained attention for their potential to positively modulate the vaginal microbiome, promoting a healthier environment for embryo implantation.

The vaginal microbiome is predominantly composed of Lactobacillus species, which are known to maintain a low pH and inhibit the growth of pathogenic organisms. This healthy microbiota is critical for a successful pregnancy, as dysbiosis can lead to adverse reproductive outcomes. Studies have shown that women with a predominance of Lactobacillus in their vaginal microbiota tend to have better fertility outcomes compared to those with dysbiotic microbiomes characterized by a higher diversity of bacteria. The administration of vaginal probiotics before ET has been proposed as a strategy to enhance the chances of successful implantation by restoring a healthy microbiota balance.

Impact of Probiotic Supplementation on Pregnancy Outcomes

A systematic review and meta-analysis conducted by Maleki-Hajiagha et al. (2025) evaluated the effect of vaginal probiotic supplementation on pregnancy rates following embryo transfer. The analysis included six studies with a total of 850 participants, comparing the clinical pregnancy rates between women receiving vaginal probiotics and control groups. The findings indicated a non-significant increase in clinical pregnancy rates among the probiotic group (37.47%) compared to the control group (31.55%), with a pooled risk ratio of 1.19 (95% CI: 0.99 to 1.44; P = 0.07).

While the increase in clinical pregnancy rates was not statistically significant, the trend suggests potential benefits of vaginal probiotics in enhancing reproductive outcomes, particularly in women with a history of RIF. This aligns with the hypothesis that probiotics may improve the endometrial environment and modulate immune responses favorably during early pregnancy.

Analysis of Clinical Trials Involving Vaginal Probiotics

The systematic review highlighted variability in study designs, probiotic formulations, and populations studied. Most included studies utilized Lactobacillus strains, with varying dosages and durations of administration, complicating direct comparisons. Notably, only one study assessed endometrial microbiota composition prior to intervention, raising questions about the personalized effectiveness of probiotics based on individual microbiota profiles.

Furthermore, the studies’ methodological quality varied, with some lacking proper randomization or control groups, which could introduce bias into the findings. The absence of standardized protocols for probiotic administration and the diverse causes of infertility among participants further contributed to the heterogeneity observed in the results.

User Perceptions and Satisfaction with Probiotic Interventions

User satisfaction with probiotic interventions has been a focal point in assessing their feasibility and acceptability. Patients expressed a high level of interest in continuing the use of probiotics, with many reporting positive experiences regarding their perceived benefits. However, concerns about potential adverse effects were noted, highlighting the importance of monitoring for any negative outcomes associated with probiotic use.

In clinical practice, it is essential to provide comprehensive counseling to patients regarding the potential benefits and risks associated with vaginal probiotics. Understanding individual preferences and experiences can guide clinicians in tailoring treatments to enhance patient satisfaction and engagement in ART protocols.

Future Directions for Probiotic Use in Fertility Treatments

The findings of the systematic review and meta-analysis suggest promising avenues for future research in the use of vaginal probiotics in fertility treatments. Future studies should aim to:

1. Standardize Probiotic Protocols: Establish clear guidelines regarding the strains, dosages, and duration of probiotic treatment to optimize their effectiveness.

2. Investigate Host Factors: Explore how individual microbiota profiles and other host-related factors influence the efficacy of probiotics in improving pregnancy outcomes.

3. Assess Long-term Effects: Evaluate the long-term outcomes of probiotic use on reproductive health and offspring development to ensure safety and efficacy.

4. Personalized Approaches: Incorporate microbiota assessments into ART protocols to tailor probiotic interventions based on individual patient profiles, particularly in those with unexplained infertility or recurrent implantation failure.

5. Expand Outcome Measures: Include more comprehensive outcome measures in clinical trials, such as live birth rates and long-term pregnancy outcomes, to provide a clearer picture of the benefits of vaginal probiotics.

FAQ

What are vaginal probiotics?
Vaginal probiotics are supplements that contain beneficial bacteria, primarily Lactobacillus strains, aimed at restoring or maintaining a healthy vaginal microbiome.

How do probiotics enhance embryo transfer success rates?
Probiotics may improve the vaginal and endometrial microbiota, creating a favorable environment for embryo implantation, thus potentially increasing pregnancy success rates.

Are there any risks associated with using probiotics during fertility treatments?
While generally considered safe, probiotics can cause mild side effects, such as discomfort or irritation. It’s important for patients to discuss any concerns with their healthcare provider.

How long should probiotics be taken before embryo transfer?
The duration of probiotic supplementation can vary, but studies suggest that starting probiotics for at least two weeks before embryo transfer may be beneficial.

Can probiotics be used alongside other treatments?
Yes, probiotics can be used as an adjunct therapy alongside other ART procedures, but patients should consult with their healthcare provider to ensure compatibility.

References

1. Maleki-Hajiagha, A., Karimi, R., Abbasi, S., Emami, N., & Amidi, F. (2025). Vaginal probiotics as therapeutic adjuncts for improving embryo transfer success rates: a systematic review and meta-analysis. BMC Pregnancy and Childbirth, 25(1), 338. https://doi.org/10.1186/s12884-025-07338-0

2. Moreno, I., García-Grau, I., Pérez-Villaroya, D., González-Monfort, M., Bahçeci, M., & Barrionuevo, M. J. (2022). Endometrial microbiota composition is associated with reproductive outcome in infertile patients. Microbiome, 10(1), 1. https://doi.org/10.1186/s40168-021-01184-w

3. Blancafort, C., & Llácer, J. (2023). Can probiotics enhance fertility outcome? Capacity of probiotics as a single intervention to improve the feminine genital tract microbiota in non-symptomatic reproductive-aged women. Frontiers in Endocrinology, 13, 1081830

4. Chen, R. Z., Wang, Y. F., Chen, P. G., Fang, C., & Li, T. T. (2024). Clinical application of the endometrial microbiota test combined with personalized treatment in patients with repeated implantation failure. Reproductive Developmental Medicine, 8(1), 18-23

5. Thanaboonyawat, I., Pothisan, S., Petyim, S., & Laokirkkiat, P. (2023). Pregnancy outcomes after vaginal probiotic supplementation before frozen embryo transfer: a randomized controlled study. Scientific Reports, 13, 11892. https://doi.org/10.1038/s41598-023-39078-6