The Vaginal Microbiome: Its Role in Fertility, Pregnancy, & Preterm Labor Risk

The vaginal microbiome plays a central role in protecting and influencing the harmonious balance of bacteria in the vaginal tract. Research has shown that bacterial infections – including sexually transmitted diseases (STDs), bacterial vaginosis (BV), urinary tract infections (UTIs), and Group B Streptococcus (GBS) – affect fertility and the risk of both preterm labor and post-partum complications.3 How does an imbalanced vaginal microbiome affect fertility? What constitutes a “healthy” vaginal microbiome? What probiotics promote an optimal microbial environment for fertility and the health and survival of the next generation? This article will address these questions.

The mechanism by which the vaginal tract is policed and protected is regulated by the vaginal microbiome. Antimicrobial peptides (AMP) – amphipathic, multifunctional molecules – are released from the epithelial cells of the female reproductive tract in response to chemical signals from the local microbial community to protect the host against inflammation and pathogen invasion. Ie, AMPs are an immunological barrier to infections in the female reproductive tract, which are alerted by dybiosis of the vaginal microbiome.4 This microbiome is influenced by hormonal changes and vice versa. Estrogen stimulates the vaginal epithelia to produce glycogen, which is metabolized by lactobacilli. These microbes produce lactic acid and organic acids that lower the vaginal pH to 3.7-4.5, making the vagina more acidic and thereby less hospitable to pathogenic bacteria.5 As a result, estrogen levels play a role in a woman’s susceptibility to vaginal infections and – as we shall see – fertility as well.

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