Uterine fibroids affect an estimated 70–80% of women by age 50, making them the most common benign tumor in women of reproductive age. Yet despite their prevalence, most women receive the same limited options: watchful waiting, hormonal suppression, or surgical intervention. Understanding the hormonal drivers of fibroid growth opens the door to strategies that actually address the root cause.
Fibroids are estrogen- and progesterone-sensitive tumors. Estrogen drives their growth — fibroid cells express significantly higher levels of estrogen receptors than normal uterine tissue, and they grow during the reproductive years when estrogen is highest, shrink after menopause when estrogen declines, and are virtually never found before puberty. Any factor that increases estrogen exposure — estrogen dominance, obesity (through aromatization in adipose tissue), xenoestrogen exposure, or impaired estrogen detoxification — increases fibroid growth rate.
Progesterone’s role is more nuanced. Some research suggests that progesterone also promotes fibroid cell proliferation through progesterone receptors in the fibroid tissue — which is why GnRH agonists that suppress both estrogen and progesterone are sometimes used clinically. However, the relative estrogen dominance picture — insufficient progesterone relative to estrogen — appears to be the more clinically relevant issue for most women with symptomatic fibroids.
A functional medicine approach to fibroid management focuses on reducing estrogen burden: supporting liver Phase I and II detoxification, rebalancing the gut estrobolome, eliminating xenoestrogen exposures, optimizing body composition to reduce aromatization, and — where appropriate — using targeted bioidentical progesterone to counterbalance estrogen’s proliferative effects on the uterus.
If you have fibroids and want to understand the hormonal picture driving them, call 844-734-2112 or reach out to our team.