Fibroids and Adenomyosis — Heavy Periods Explained

Uterine fibroids (leiomyomas) are noncancerous growths that develop in or on the uterus. They are extraordinarily common — by age 50, up to 80% of women will have at least one fibroid, though many will never know because fibroids often cause no symptoms.

Fibroids are made of smooth muscle and fibrous connective tissue and range in size from a tiny seedling invisible to the naked eye to large masses that can distort the uterus. They can grow as a single nodule or in clusters. Their location matters more than their size for determining symptoms: submucosal fibroids (protruding into the uterine cavity) are most likely to cause heavy bleeding and fertility issues, intramural fibroids (within the uterine wall) may cause pain and pressure, and subserosal fibroids (on the outer surface) may press on the bladder or bowel.

The exact cause of fibroids isn't fully understood, but they are estrogen- and progesterone-dependent — meaning they grow during reproductive years and typically shrink after menopause. Risk factors include age (most common in the 30s and 40s), family history, Black race (2–3 times higher prevalence and typically more severe), obesity, early onset of menstruation, and vitamin D deficiency.

Most fibroids are benign, with less than 1 in 1,000 being cancerous (leiomyosarcoma). However, the symptoms they cause — heavy bleeding, pain, pressure, and potential fertility complications — can significantly impact quality of life and should not be dismissed.

Adenomyosis occurs when the endometrial tissue (the tissue that normally lines the inside of the uterus) grows into the muscular wall of the uterus (the myometrium). Each menstrual cycle, this displaced tissue continues to thicken, break down, and bleed — but within the muscle wall, causing the uterus to enlarge, become boggy, and produce intense pain and heavy bleeding.

While fibroids are distinct growths that can be individually identified and removed, adenomyosis is diffuse — the endometrial tissue is woven into the muscle itself, making it harder to treat surgically without removing the uterus. Think of fibroids as marbles in bread dough versus adenomyosis as chocolate chips melted into the dough.

Adenomyosis is most commonly diagnosed in women aged 35–50, though it can occur at any reproductive age. It affects an estimated 20–35% of women, though the true prevalence is likely higher since it was historically only diagnosed after hysterectomy. Modern MRI and transvaginal ultrasound can now detect it non-invasively.

The two conditions frequently coexist — up to 40% of women with fibroids also have adenomyosis. Both cause heavy bleeding and pain, but adenomyosis tends to produce more diffuse, crampy pain throughout the uterus, while fibroids may cause more localized pressure symptoms. Adenomyosis is also strongly associated with endometriosis, and many women have both conditions.

Knowing which condition (or combination) is driving your symptoms is essential for choosing the right treatment, so accurate diagnosis matters significantly.

Heavy menstrual bleeding (menorrhagia) is defined medically as losing more than 80ml of blood per cycle — but since nobody measures their menstrual blood, practical benchmarks are more useful.

Your bleeding is likely heavy if you soak through a regular pad or tampon in less than 2 hours, you need to use double protection (pad plus tampon) regularly, you pass blood clots larger than a quarter (2.5cm), your period lasts longer than 7 days, you need to change menstrual products during the night, or your bleeding restricts your daily activities.

Heavy bleeding matters not just because of the inconvenience but because of its health consequences. The most significant is iron-deficiency anemia, which develops when blood loss exceeds your body's ability to replace iron stores. Symptoms of period-related anemia include persistent fatigue, weakness, shortness of breath during normal activity, pale skin, dizziness, cold hands and feet, and difficulty concentrating.

Remarkably, many women with objectively heavy bleeding don't realize it's abnormal because they've never known anything different. They've adapted — carrying extra supplies, planning their lives around their periods, accepting fatigue as their baseline. One study found that 50% of women with menstrual blood loss exceeding 80ml per cycle considered their bleeding "normal."

If any of the benchmarks above apply to you, bring it up with your healthcare provider. A simple blood count can check for anemia, and further investigation can determine whether fibroids, adenomyosis, or another condition is causing the heavy flow. Heavy periods are treatable — you don't have to just cope.

Treatment depends on symptom severity, fibroid size and location, whether adenomyosis is present, your age, and your fertility goals. The range of options has expanded significantly in recent years.

Medical management is typically the first approach. The hormonal IUD (Mirena) is highly effective for reducing heavy bleeding from both fibroids and adenomyosis. Tranexamic acid, taken during your period, reduces blood loss by 30–50% by preventing clot breakdown. Hormonal birth control (pills, patches, or rings) can reduce bleeding and pain. GnRH agonists can shrink fibroids temporarily by creating a low-estrogen state, often used before surgery to reduce fibroid size.

Minimally invasive procedures for fibroids include uterine artery embolization (UAE), which blocks blood supply to fibroids causing them to shrink, and MRI-guided focused ultrasound, which uses heat to destroy fibroid tissue. Myomectomy surgically removes individual fibroids while preserving the uterus and is the preferred option for women who want to maintain fertility.

For adenomyosis specifically, treatment options are more limited because the disease is diffuse. The hormonal IUD is often the most effective non-surgical option. Endometrial ablation can reduce bleeding but is only appropriate for women who have completed childbearing. Adenomyomectomy (surgical excision of adenomyotic tissue) is possible in some cases but technically challenging.

Hysterectomy remains the only definitive cure for both conditions but is considered a last resort, especially for women who want children. When all other treatments have failed and quality of life is significantly impaired, it can be a life-changing decision that many women report wishing they'd made sooner.

Iron supplementation is essential alongside any treatment if anemia is present — treating the bleeding without repleting iron stores will leave you feeling exhausted.

Both conditions can affect fertility, but the impact varies significantly depending on the type, location, and severity of disease.

For fibroids, location is the critical factor. Submucosal fibroids — those that distort or protrude into the uterine cavity — have the clearest impact on fertility. They can interfere with embryo implantation, increase miscarriage risk, and are generally recommended for removal before fertility treatment. Intramural fibroids larger than 4–5cm may also affect fertility, though the evidence is less definitive. Subserosal fibroids (on the outside of the uterus) generally don't impair fertility unless they're very large.

Myomectomy (surgical removal of fibroids) can improve fertility outcomes when fibroids are distorting the uterine cavity. However, surgery itself creates scar tissue, so the decision to operate should weigh the potential fertility benefit against surgical risks. Recovery time before attempting conception is typically 3–6 months.

Adenomyosis affects fertility through several mechanisms: it alters uterine contractility, impairs endometrial receptivity, and may interfere with embryo implantation. Research increasingly shows that adenomyosis reduces IVF success rates. Medical suppression with GnRH agonists before embryo transfer is one strategy being studied to improve outcomes.

If you have either condition and are planning pregnancy, early consultation with a reproductive specialist is valuable. They can assess whether treatment before conception is advisable and help you develop a timeline that accounts for any needed interventions and recovery periods. For some women, fertility preservation through egg freezing may be worth considering while treatment decisions are made.

Iron deficiency caused by heavy menstrual bleeding is one of the most common nutritional deficiencies in premenopausal women worldwide, yet it's frequently overlooked — even by healthcare providers who may not connect your fatigue, brain fog, or exercise intolerance to your periods.

Iron is essential for producing hemoglobin, the protein in red blood cells that carries oxygen throughout your body. When iron stores are depleted, your body can't make enough healthy red blood cells, leading to iron-deficiency anemia. But even before you become anemic, low iron stores (ferritin) can cause significant symptoms.

Early signs of iron depletion include fatigue that doesn't improve with sleep, difficulty concentrating and brain fog, reduced exercise capacity and feeling winded easily, restless legs (especially at night), increased anxiety and irritability, hair thinning and brittle nails, frequent infections (iron supports immune function), and cravings for ice, dirt, or starch (a condition called pica).

As anemia progresses, symptoms worsen to include pale skin and inner eyelids, rapid heartbeat, shortness of breath with minimal exertion, dizziness and lightheadedness, and cold hands and feet. Severe anemia can cause chest pain and requires urgent treatment.

If you have heavy periods, ask your doctor to check a complete blood count (CBC) and ferritin level. Ferritin below 30 ng/mL is considered low, even if your hemoglobin is still technically "normal." Treatment involves addressing the underlying cause of heavy bleeding while simultaneously repleting iron through supplementation (look for ferrous sulfate, ferrous bisglycinate, or iron polysaccharide complex) and iron-rich foods. Intravenous iron infusions are an option when oral supplements aren't tolerated or aren't working fast enough.