A Potential Link Between Oral Microbiota and Female Reproductive Health

Abstract

Oral cavity dysbiosis is associated with numerous inflammatory diseases, including diabetes, inflammatory bowel diseases, and periodontal disease. Changes in the oral microenvironment lead to bidirectional interactions between pathogens and individual host systems, which may induce systemic inflammation. There is increasing evidence linking the condition of the oral cavity with the most common causes of female infertility, such as polycystic ovary syndrome and endometriosis, as well as gestational complications, e.g., low birth weight, preterm delivery, and miscarriages. This review highlights the composition of the female oral microbiome in relation to infertility-related disorders, such as endometriosis and polycystic ovary syndrome, and provides a comprehensive overview of the current state of knowledge on the relationship between a dysbiotic oral microbiome, pregnancy, and its impact on the female reproductive tract.

Keywords: endometriosis; female reproductive tract; infertility; oral dysbiosis; oral microbiome; periodontal health; polycystic ovary syndrome.

Figure 1

A potential link between oral dysbiosis and systemic health. (The figure was created using BioRender.com). Oral cavity ecological imbalance affects individual host systems. Periodontal diseases accompanied by oral dysbiosis are associated with the development of Alzheimer’s disease, cardiovascular disease, respiratory infections and pneumonia, adverse pregnancy outcomes, diabetes and insulin resistance, carcinogenesis, inflammatory bowel diseases, and disruptions in the reproductive system [21,22,23,24,25,26,27,28,29,30,31,32].

Figure 2

Potential direct and indirect mechanisms of oral pathogens’ actions on the fetus. (The figure was created using BioRender.com). Periodontal pathogens affect the fetus through two possible mechanisms: direct action, whereby microbes from disrupted oral microbiome translocate via hematogenous dissemination to the fetal circulation and cause bacteriemia; or indirect actions via oral bacterial endotoxins and inflammatory mediators entering the systemic circulation and causing systemic inflammation [67,70]. Systemic inflammatory response is induced by bacterial lipopolysaccharides (LPSs) and mediated by proinflammatory cytokines, including interleukins (IL-1 and IL-6) and tumor necrosis factor (TNF-α). Both mechanisms cause intrauterine and placental bacteriemia, leading to adverse pregnancy outcomes.

Figure 3

Possible effect of oral dysbiosis on female infertility. (The figure was created using BioRender.com). Oral dysbiosis and periodontal pathogens associated with it, such as F. nucleatum, P. gingivalis, and T. forsythia, may translocate from disrupted oral microenvironment and affect female reproductive functions; directly, via inducing local inflammation in the pelvic peritoneum among women with endometriosis, causing exacerbation of the disease; or indirectly, via promoting inflammation, insulin resistance, or oxidative stress, which may lead to PCOS development [84,85,86,89,104,137,139].