Uterine Fibroids: What They Are, Why They Grow & How to Support Your Body

Uterine fibroids are so common that they're often dismissed as unremarkable — "most women have them," doctors say, "and most don't cause problems." While it's true that many fibroids are asymptomatic, the dismissal misses the significant proportion of women for whom fibroids are behind some of the most debilitating menstrual symptoms they experience: periods that soak through products hourly, iron deficiency anaemia from chronic blood loss, pressure and pain in the pelvis, and fertility challenges.

Fibroids are not inevitable, and they don't appear randomly. Understanding what drives their growth gives you real tools — both for prevention and for managing existing fibroids alongside medical care. This article covers everything you need to know.

What Uterine Fibroids Are

Uterine fibroids (also known as leiomyomas or myomas) are benign (non-cancerous) growths that develop from the smooth muscle tissue of the uterine wall (myometrium). They are composed primarily of muscle and fibrous connective tissue. Fibroids can range from microscopic to large enough to distort the shape of the uterus significantly — the size of a grape to the size of a grapefruit and beyond.

Despite being extremely common, the mechanisms underlying fibroid development are not fully understood. What is clear is that they are hormone-sensitive: they grow in response to estrogen and progesterone, and they typically shrink after menopause when these hormones decline. They are almost never cancerous — uterine sarcoma, the malignant form, is rare (less than 1 in 1000 cases of fibroids) and tends to present with rapid growth rather than the slow growth typical of fibroids.

How Common Are Fibroids

Fibroids are extraordinarily common. By age 50, 70–80% of women will have developed at least one fibroid, though many will remain unaware because the fibroids are small and symptomless. Among women who are symptomatic, approximately 25–50% will have symptoms significant enough to affect their quality of life or require treatment.

There is a striking and well-documented racial disparity: Black women are 2–3 times more likely to develop fibroids than white women, develop them at a younger age (often in their 20s and 30s rather than 40s), tend to develop larger and more numerous fibroids, and are more likely to have severe symptoms. They are also more likely to face delays in diagnosis and barriers to accessing specialist care. These disparities reflect systemic inequities in healthcare rather than any inherent biological difference.

Types of Fibroids and Their Location

The location of a fibroid largely determines what symptoms it produces:

• •Submucosal fibroids — growing into the uterine cavity; even small submucosal fibroids can cause significant heavy bleeding and fertility problems because they distort the cavity and interfere with implantation
• •Intramural fibroids — within the muscle wall itself; the most common type; cause heaviness, pressure, and — when large — heavy periods and bulk symptoms
• •Subserosal fibroids — growing outward from the outer surface of the uterus into the pelvic cavity; may press on the bladder or bowel causing urinary frequency, urgency, or constipation, but often don't cause heavy bleeding
• •Pedunculated fibroids — attached to the uterus by a stalk, either inside the cavity or outside; the stalk can twist (torsion), causing acute pelvic pain
• •Cervical fibroids — growing in the cervical tissue; less common but can cause pain, bleeding, and affect fertility

Symptoms and When They Occur

As noted, many fibroids are asymptomatic. When symptoms are present, the most common include:

• •Heavy menstrual bleeding (menorrhagia) — the most common symptom; can be severe enough to cause iron deficiency anaemia
• •Prolonged periods — bleeding for more than 7 days
• •Pelvic pain and pressure — a heaviness, fullness, or aching in the lower abdomen
• •Urinary symptoms — frequency, urgency, or incomplete emptying (from fibroid pressure on the bladder)
• •Constipation — from fibroid pressure on the rectum
• •Pain during sex — depending on fibroid location
• •Enlarged abdomen — large fibroids can cause the abdomen to protrude visibly
• •Fertility and pregnancy complications — particularly with submucosal fibroids; associated with implantation failure, miscarriage, and preterm birth

What Drives Fibroid Growth

Estrogen dominance

Fibroids have a high density of estrogen receptors and are highly responsive to estrogenic stimulation. Excess estrogen relative to progesterone — from any of the sources discussed in the estrogen dominance article — drives fibroid proliferation. This is why fibroids are more common and grow faster in environments of relative estrogen dominance: obesity (which increases aromatase activity in fat tissue), poor estrogen clearance through the liver and gut, and exposure to environmental estrogens (xenoestrogens).

Insulin resistance

Insulin and IGF-1 are growth factors that stimulate fibroid cells to proliferate. Insulin resistance — common in women with metabolic syndrome, PMOS (formerly PCOS), and those eating a high-refined-carbohydrate diet — significantly increases fibroid growth risk and rate. Blood sugar regulation is a key prevention and management strategy.

Vitamin D deficiency

Vitamin D deficiency is strongly associated with fibroid development — and notably, deficiency is more prevalent in Black women, which may partly contribute to the racial disparity in fibroid rates. Vitamin D has anti-proliferative effects on fibroid cells in laboratory studies. Optimising vitamin D to 60–80 ng/mL is an important part of a fibroid-management protocol.

Chronic inflammation

Fibroids have an inflammatory microenvironment — they produce inflammatory cytokines that promote their own growth and survival. Systemic inflammation from diet, gut dysbiosis, and chronic stress drives fibroid activity. Anti-inflammatory interventions are therefore directly therapeutic rather than merely supportive.

Medical Treatment Options

For women with symptomatic fibroids, there is a range of medical and procedural options:

• •Levonorgestrel-releasing IUD (Mirena): reduces heavy bleeding significantly for many women by delivering progesterone locally; does not shrink fibroids but manages the most disruptive symptom
• •GnRH agonists/antagonists (Lupron, Orlissa): suppress estrogen production to shrink fibroids; used short-term before surgery or as bridge therapy; cause temporary menopausal symptoms and bone loss with long-term use
• •Uterine artery embolisation (UAE): minimally invasive; cuts off blood supply to fibroids, causing them to shrink; effective for most fibroid types; not recommended for women actively trying to conceive
• •Myomectomy: surgical removal of fibroids while preserving the uterus; the preferred surgical option for women who wish to conceive; fibroids can recur after myomectomy
• •Hysterectomy: the only definitive cure; appropriate for women who have completed their families and whose symptoms are severely affecting quality of life after other options have been tried

Natural Supportive Approaches

Natural approaches to fibroid management work by addressing the hormonal and inflammatory drivers of fibroid growth. They are most appropriate as complementary strategies alongside medical care, particularly for women with mild to moderate symptoms or those preparing for or recovering from procedures.

Anti-inflammatory, estrogen-clearance diet

Eat a whole-food diet rich in cruciferous vegetables, leafy greens, and colourful produce. Cruciferous vegetables support liver estrogen metabolism through DIM and I3C. Prioritise omega-3-rich foods (oily fish, flaxseed, walnuts). Significantly reduce refined sugar, processed foods, refined seed oils, red meat, and alcohol. Consider a dairy reduction trial. The fibre in a plant-rich diet supports estrogen clearance through the bowel and feeds a healthy estrobolome.

Optimise vitamin D

Test your vitamin D level and supplement to achieve a blood level of 60–80 ng/mL. This is one of the most evidence-supported natural interventions for fibroid management and prevention.

Support estrogen metabolism

DIM (100–200 mg per day), calcium d-glucarate (500–1000 mg per day), B vitamins for methylation support, and addressing gut dysbiosis all support the liver and gut in clearing estrogen efficiently — reducing the estrogenic environment that drives fibroid growth.

Manage heavy bleeding in the interim

For women experiencing heavy periods from fibroids, addressing the iron deficiency that commonly results is essential. Ferritin should be tested and iron supplemented aggressively (bisglycinate form for tolerability). Nattokinase, serrapeptase, and bromelain are systemic enzyme supplements used in some natural medicine traditions to help reduce fibroid bulk and associated bleeding — research is limited but clinical experience is promising.

When Surgery Makes Sense

Natural approaches are genuinely valuable for fibroid prevention and for managing mild to moderate symptoms — but there are clear situations where medical or surgical intervention is the right choice, and pursuing it is not a failure of the natural approach:

• •Severe iron deficiency anaemia from blood loss that is not adequately controlled with natural approaches
• •Fibroids causing significant pain, pressure symptoms (urinary retention, severe constipation), or pelvic pressure that is substantially affecting quality of life
• •Submucosal fibroids significantly distorting the uterine cavity in a woman trying to conceive
• •Rapid fibroid growth that warrants investigation to rule out uterine sarcoma

Make treatment decisions collaboratively with a gynaecologist who understands both the medical options and your personal priorities around uterine preservation, fertility, and quality of life.