Key Points
- Maintaining a balanced microbiome is especially critical for women, as it influences reproductive health, menstrual cycles and fertility.
- Women's health is shaped by many interacting factors-hormones, immunity, genetics and the microbiome.
- Closing the women's health gap will require more research, better care and greater awareness.
Women's bodies experience a unique set of health challenges that are different from men's, which is why some illnesses affect only women or show up far more often in women than in men. Notably, many of these conditions, such as uterine fibroids, polycystic ovarian syndrome (PCOS) and endometriosis, are shaped by women's reproductive organs, hormones and genetics, and don't currently have a cure. Interventions can manage symptoms or slow progression, but they do not erase the health challenges.
In recent years, scientists have discovered that the microbiome may impact some of the most common conditions in women's health and play an important role in regulating hormones, immunity and inflammation. While research that deeply explores such connections remains limited, it is clear that insights into the microbial mechanisms underpinning women's health are critical for understanding how women's bodies function-and how to keep them healthy.
Microbiome and Women's Health
Microbiome balance is especially important for women because it can influence reproductive health, menstrual cycles and even fertility. By studying the microbiology of related health conditions, particularly uterine fibroids, PCOS and endometriosis, more closely, researchers may uncover how microorganisms can either protect women's health or contribute to disease.
Uterine Fibroids
Uterine fibroids are the most common tumors found in women of reproductive age. They are non‑cancerous growths that develop in the muscular wall of the uterus (the womb) and can range from tiny, unnoticed nodules to masses large enough to distort the uterus. More than 80% of Black women and up to 70% of white women will develop fibroids by age 50, and many never feel symptoms. But for others, fibroids can cause heavy menstrual bleeding, anemia, pelvic pressure, infertility or, in up to 25% of cases, pregnancy loss.
Fibroids begin when a single muscle cell in the uterus develops a genetic change that causes it to grow abnormally. Over time, this cell multiplies and forms a tumor made of smooth‑muscle cells and dense tissue. Two genes (MED12 and HMGA2) are responsible for most fibroid growth, and hormones like estrogen and progesterone fuel their development.
Evidence suggests that microorganisms in the body may play a role in fibroid growth. One key finding is the connection between gut microbes, their collective genetic materials and estrogen (the hormone that fuels fibroids). Some gut bacteria harbor genes that can help process and balance estrogen, collectively known as the estrobolome. When these bacteria are out of balance, estrogen may build up instead of being broken down and cleared from the body, which can stimulate fibroid growth. In this manner, some bacteria belonging to the families Lachnospiraceae and Actinomycetaceae may make fibroids more likely.
Just like the gut, the microorganisms and associated genetic material in the vagina may also matter. Normally, healthy bacteria like lactobacilli protect the uterus and vagina by keeping the environment acidic, producing natural antimicrobials and supporting the body's defenses against infection. But when vaginal health is compromised, inflammation and immune changes can occur. This imbalance (called dysbiosis) might create conditions that encourage fibroids to grow. When the vaginal microbiome is disrupted, the resulting inflammation, changes in estrogen processing and weakened local immune defenses may enhance fibroid growth. While research on the vaginal microbiome's connection to uterine fibroids is still emerging, scientists already know that the vaginal microbial population is tied to other gynecological issues.
