What Causes Uterine Fibroids?

reasons for fibroids

Updated August 8th, 2023

The real question is, what causes fibroids?

This is the never-ending question (or debate). Some people claim it is one thing or the other, but the truth is, there are many possible factors.

Here’s what we *do* know, and how we ultimately can learn to support our body in a way that leads to the diminished likelihood or continued growth of fibroids. And this is true whether they be submucosal fibroids, intramural fibroids, if they are inside of the uterus, outside of the uterus, or on the wall of the uterus.

These non-cancerous growths can significantly impact a person’s quality of life and grow to the size of a melon. Even small fibroids can lead to various uncomfortable symptoms, which we’ll cover in a moment. The severity of these symptoms can range from mild to debilitating, affecting daily activities, work productivity, and overall emotional well-being.

Women with fibroids may experience reduced energy levels, disrupted sleep patterns, and limited physical activity due to pain and discomfort. The potential impact on fertility and the emotional strain caused by the uncertainty of future reproductive health can also contribute to decreased quality of life.

Addressing fibroid-related quality of life issues often involves a combination of medical management, minimally invasive procedures, or surgical interventions, tailored to the individual’s symptoms and goals to restore their overall well-being and vitality.

Before we cover the factors that provide a higher risk for fibroids, let’s quickly go over some of the major symptoms of uterine fibroids:

Symptoms Of Fibroids

  • Pelvic pain or pelvic pressure
  • Blood loss
  • Heavy menstrual bleeding
  • Frequent urination
  • Low back pain
  • Menstrual cycle being thrown off
  • Other severe symptoms like chronic pain, bloating, and the fibroid(s) growing to the size of a baby

Please note, these are not treatment options per se, but are underlying risk factors that combine to make your uterus more hospitable to fibroids.

Big Factors

Estrogen excess (or dominance). We do know this hormone levels are a huge factor when it comes to fibroids. When there’s too much estrogen circulating in our body without enough progesterone to balance it out, or our body favors the 4-OH or 16-OH pathways in metabolizing estrogen, it is a feeding ground for large fibroids. High estrogen levels are often a big part of the heavy periods and heavy bleeding we see with fibroids.

Excess estrogen has a lot of factors at play, from perimenopause to xenoestrogens to thyroid and adrenal issues. What can make the situation tough, though, is this fibroids have can have progesterone receptors alongside estrogen receptors (in some cases,

progesterone blockers known as SPRMs have been used to reduce fibroids). So it’s not always clear-cut.

If you go to an allopathic doctor and learn you have fibroids, they will often recommend gonadotropin-releasing hormone agonists (gnrh agonists) in order to reduce fibroid size, as these make your estrogen plummet. The problem is the other side of the coin – side effects like hot flashes, aging skin, bone deterioration, vaginal dryness and more can occur.

Liver issues. This is a huge factor, which connects directly to excess estrogen. How your liver is metabolizing (or “detoxing”) estrogen is just as – or maybe more – important than estrogen in and of itself.

Our liver oversees 750 processes in our body, and unfortunately, metabolizing estrogen can get pushed to the back of the line, particularly when it needs to focus on things like alcohol, caffeine, drugs, and pesticides first.

There are also genetic propensities to impaired detoxification. I talk more about this below.

Liver support is essential when you have fibroids, and I’ll talk more about this is in an upcoming post.

Adrenal dysfunction. The often overlooked adrenals are also a big part of the picture. Stress triggers cortisol output, which can negatively impact progesterone levels, once again allowing for estrogen to go unchecked which feeds fibroid growth.

Thyroid Disorders. Studies have shown an association between a low functioning thyroid and an increased risk of fibroids. Here are a few studies:

Relationship between thyroid disorders and uterine fibroids among reproductive-age women

Overt hypothyroidism is associated with the presence of uterine leiomyoma: a retrospective analysis

Uterine Fibroids Increase the Risk of Thyroid Cancer


Low Vitamin D. There are quite a few studies that connect low vitamin D levels with fibroids, including this one and this one.

Gene variations. Several genes play a part of the processing, or metabolization, of estrogen. That’s a fancy way of saying after your body uses estrogen, your liver breaks it down to help remove it from your body so that it doesn’t cause issues like fibroids and caner. So if you have genes that have what are called “variations” or “mutations” on them, your body may be slower in processing estrogen, which can lead to higher levels.

Some of the more well-known genes that impact estrogen metabolism include CYP450, COMT, and UGT. CYP450 enzymes play major roles in Phase 1 estrogen metabolism in the liver, which is the first phase of detoxifcation. COMT and UGT work in Phase 2, which is the second phase of detoxification, where the toxin from Phase 1 is made water-soluble and no longer a threat.

I’ll do a longer post on this process of estrogen detoxification, but for now, know that if your CYP450 aren’t up to perfect working order, that can mean estrogen may favor the 4-OH or 16-OH pathways, both of which are associated with fibroid growth. If COMT and UGT aren’t fully functioning, the process of detoxificaiton can get backed up, maintaining higher and more threatening levels of estrogen.

Understanding your unique genetic code can guide you to what specific nutrients your body needs to fend off fibroid growth. That’s why I recently started utilizing 3×4 genetic testing with my clients.

Xenoestrogens. Xenoestrogens also play a role in fibroid growth, as these are chemicals that act as estrogen in the body. They will actually lock into your estrogen receptors, taking the place of your own estrogen! Unfortunately, they are tougher for the body to detoxify and move out, and are often stored in our tissues.

One of the most important things to do to combat xenoestrogens is to pay attention to the amount of chemicals in your life and environment. Remove as much plastic from your day-to-day as you can (don’t drink or eat out of plastic!), change your hair, face, and body care products to non-toxic options, drink reverse osmosis (with minerals added) or distilled water, and purchase house-cleaning products that are chemical-free.

I’ll cover physical detox supports that help move out xenoestrogens in another post. In the meantime, check out my interview with Environmental Toxins Expert Lara Adler, Environmental Toxins Can Wreck Your Hormones & What You Can Do About It.

Surgical Treatments

I dive more deeply into your allopathic and surgical medical treatment options in Pros And Cons Of Surgical Interventions For Fibroids, but I did want to note a few of those options here:

  • Uterine Artery Embolization or Uterine Fibroid Embolization (UFE), which cuts off the blood supply to the fibroids
  • Endometrial ablation (this does not get rid of the fibroid, but stops the bleeding fibroids can cause)
  • Major surgery: Myomectomy (which is what I had) or hysterectomy. Though these can be performed laparoscopically depending on the size and location of the fibroid(s), meaning a small incision vs. a large cut, they are still major surgeries and should be taken under deep consideration.

Just a quick reminder that the quickest way to get a fibroid diagnosis is through a pelvic ultrasound (a routine pelvic exam will NOT let you know if you have fibroids), though many surgeons will order magnetic resonance (MRI) before surgery as it’s more exact than an ultrasound. This way they know the location of the fibroid or fibroids before going in for surgery.

Pulling It All Together

These are some of the factors the influence fibroid growth, but there are many more issues at play, including emotional and spiritual reasons. The journey of managing fibroids can lead to reflections on the body’s resilience, fostering a sense of connection between physical health and spiritual well-being. Some of us may view our experiences with fibroids as an opportunity for personal growth, resilience, and a deeper understanding of their own body and its vulnerabilities.

I dive into all of this and a whole lot more in my Fibroids 101 course. We also deep dive fibroids in our live program, Perimenopause Like A Boss so you can get to the root cause(s) of why you are dealing with fibroids. Join us for our next session starting Sep. 11th!

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