Fertility and the Vaginal Microbiome: The Research Behind Femceive

This article explores the emerging science behind the vaginal microbiome’s role in fertility and how specific strains of probiotics, such as Femceive, may help improve reproductive outcomes. It draws from recent clinical studies and biological insights to explain the impact of Lactobacillus dominance during the fertility cycle.

Understanding the Vaginal Microbiome

Unlike the gut microbiome, the vaginal microbiome is characterised by low diversity and high dominance of the Lactobacillus genus—particularly L. crispatus. These bacteria produce lactic acid to help maintain an acidic vaginal pH, which provides natural defence against pathogens.

When this balance is disrupted, the risk of bacterial vaginosis (BV) increases. BV is marked by a decline in Lactobacillus species and a rise in potentially harmful bacteria such as Gardnerella, Atopobium, and Prevotella. This disruption can negatively impact fertility and implantation.

Lactobacillus Dominance and Fertility Outcomes

Several studies have provided quantitative insights into the relationship between vaginal microbiota composition and fertility outcomes:

• Women with a dominant Lactobacillus profile (>90%) had higher rates of term pregnancy and live births.
• Non-predominance of the genus Lactobacillus (<90%) was directly associated with higher rates of miscarriage and abortion.
• Women with an unfavourable vaginal microbiota were 7 times less likely to achieve pregnancy during IVF treatment.
• The degree of dominance of L. crispatus was found to be a significant factor; women with a favourable profile and even <60% L. crispatus still had high chances of achieving pregnancy.
• Women who did not achieve pregnancy after ART showed significantly higher alpha diversity in their vaginal microbiota, indicating that less diversity favours ongoing pregnancy.
• Women with abnormal microbiota had a 1.4× lower chance of pregnancy after IVF compared with women with normal microbiota.

Clinical Evidence on Probiotic Use

According to international definitions (WHO, ISAPP), probiotics are “live microorganisms, which when administered in adequate amounts confer a health benefit on the host.” Research supports their use for restoring a Lactobacillus-dominant vaginal microbiome:

• Oral supplementation with L. rhamnosus and L. fermentum restored healthy vaginal microbiota in up to 82% of women with previous vaginal dysbiosis.
• L. plantarum has been shown in mouse models to colonise the vaginal environment, eliminate pathogens, and reverse inflammation-induced infertility.
• In a study using a lipopolysaccharide (LPS)-induced inflammation model in mice, L. plantarum was able to reverse infertility caused by inflammation of the vaginal tract.

Application Across the Fertility Cycle

Supporting the vaginal microbiome is relevant across the entire reproductive journey:

• Preconception: Helps prepare the endometrial environment for implantation
• Two-week wait: Maintains microbial balance during the implantation window
• Pregnancy: Especially important in the first 20 weeks when microbial stability impacts gestational health
• Postnatal: May assist in recovery and reduce recurrence of infections

Who Might Benefit Most?

Probiotic support may be especially valuable for women with:

• Recurrent vaginal infections
• Endometriosis
• Recent or ongoing antibiotic use

References

1. Younis, N. & Mahasneh, A. (2020). Probiotics and the envisaged role in treating human infertility. Middle East Fertility Society Journal, 25(1).
2. Bernabeu, A. et al. (2019). Effect of the vaginal microbiome on the pregnancy rate in women receiving ART. Journal of Assisted Reproduction and Genetics, 36(10), 2111–2119.
3. Moreno, I. et al. (2016). Evidence that the endometrial microbiota has an effect on implantation. Am. J. Obstet. Gynecol., 215, 684–703.
4. Singer, M. et al. (2019). Vaginal microbiota and IVF pregnancy outcomes: A meta-analysis. Journal of Gynecology Obstetrics and Human Reproduction, 48(4), 223–229.
5. Bhandari, P. et al. (2016). Positive effect of L. plantarum in reversing LPS-induced infertility. Journal of Medical Microbiology, 65(5), 345–350.