The causes of uterine fibroids may not be fully understood, but hormones play a pivotal role in their development.

What Causes Uterine Fibroids? The Role of Hormones in Fibroid Development and Treatment

by Charlotte

Pain is how the body tells us that something is wrong. For many women, however, the pain and discomfort associated with uterine fibroids may go undiagnosed. For too many, it is a pain they try to ignore. But uterine fibroids should not be taken lightly; the pain they cause can be anything from inconvenient to debilitating, and its effects can reverberate throughout your everyday life. 

Despite the prevalence and impact of fibroids, they are poorly understood by many women and rarely discussed, leaving them with unanswered questions about what to do—and what not to do—to optimize their health. So what causes uterine fibroids? What are your treatment options? And how can hormones help—or hurt—you?

By exploring the answers to these questions, you can gain a deeper understanding of uterine fibroids and get the support you need to feel your best.

What Causes Uterine Fibroids?

Uterine fibroids are growths in or on the uterus and typically noncancerous. These are generally found in three places:

  • Submucosal fibroids: in the uterine cavity
  • Intramural fibroids: within the wall of the uterus
  • Subserosal fibroids: on the outside of the uterus

These may occur as a single growth or a grouping of them, and each can be as small as less than an inch or as large as eight inches or even more. In rare cases, fibroids may be malignant.

The exact cause of uterine fibroids remains unknown. However, evidence has long suggested that both estrogen and progesterone play a role in their development and subsequent growth, which explains why they typically occur during a woman’s childbearing years and shrink after menopause. More recently, a study published in the Journal of Clinical Endocrinology & Metabolism found that testosterone could also have a significant impact, particularly as women approach menopause. As Jason Y.Y. Wong, Sc.D, of Stanford University School of Medicine, lead author of the study, explains, “Our research suggests women undergoing the menopausal transition who have higher testosterone levels have an increased risk of developing fibroids, particularly if they also have higher estrogen levels.”

But fibroids don’t necessarily point to abnormal hormone levels; some studies have found that 70-80% of women will have had uterine fibroids by the time they are in their 50s. While race, ethnicity, weight, diet, and family history all inform fibroid risk, this overwhelming prevalence of fibroids suggests that they can occur in women whose hormone levels are within a normal range. The U.S. Department of Health & Human Services, on the other hand, says that the incidence rate for women under 50 is 20-80%. This disparity may be accounted for by methodological differences between studies and the fact that most women are asymptomatic. However, even in women who do experience symptoms, they may go undiagnosed.

The Symptoms and Dangers of Uterine Fibroids

The symptoms of uterine fibroids are varied and can range from mild to severe. In some cases, they are constant, in others they are occasional, and they can include:

  • Pain in the pelvic area and back
  • Pain during sex
  • A feeling of pressure in the abdomen
  • Swelling and bloating in the abdomen
  • Heavy, prolonged periods
  • Severe menstrual cramps
  • Bleeding between periods
  • Pressure on bladder causing frequent urination or incontinence
  • Painful pressure in the rectum
  • Constipation

Any of these symptoms can be disruptive. Pain can interfere with functionality and keep you from living the life you want. Pain during sex can prevent you from experiencing intimacy and may create distance in your relationship. Frequent urination can interrupt everyday activities and be an overall source of frustration. In other words, the symptoms of uterine fibroids can have physical and emotional effects that impact multiple areas of your life.

In some cases, fibroids may also cause infertility and present a significant danger for women who are pregnant. Although the vast majority of women who have uterine fibroids have perfectly normal pregnancies, evidence suggests that “uterine fibroids are associated with an increased rate of spontaneous miscarriage, preterm labor, placenta abruption, malpresentation, labor dystocia, cesarean delivery, and postpartum hemorrhage.” 

Despite the potentially destructive effects of uterine fibroids, many women do not bring up their symptoms to their health care practitioner. After all, symptoms are often subtle enough to ignore without much difficulty. You may attribute your symptoms to other phenomena or think they are just a part of life as a woman—it’s “just” having your period, it’s “just” perimenopause. Some women also feel embarrassed to discuss their symptoms with anyone. But you do not have to live with discomfort or distress.

The Role of Hormone Therapy in Uterine Fibroid Treatment 

While many questions remain about what causes uterine fibroids, there is plenty known about how to treat them and their symptoms. Today, there is a plethora of treatment options available, including medical management, ultrasound therapy, uterine artery embolization, and a variety of surgical procedures. Which type of treatment is best for you will depend on the nature of your symptoms, their severity, your stage of life, and your personal preferences. For example, mild to moderate pain symptoms may be managed with simple NSAIDs while women with severe symptoms that have not been successfully addressed by other treatment options may choose to undergo a hysterectomy—the only curative treatment for uterine fibroids.

Regardless of the type of treatment you initially choose, selecting a health care provider with expertise in hormone health can be critical to ensuring you get the best care throughout your treatment journey. This is due to both the vital role hormones play in uterine fibroid symptoms and the impact of many uterine fibroid treatments on hormones.

While both estrogen and progesterone are known to impact fibroid development, combination contraception, progestin-only contraception, and progesterone replacement therapy may be used to reduce or eliminate heavy menstrual bleeding and cramps associated with uterine fibroids. In fact, these therapies are often a first-line treatment option for women with symptomatic fibroids. The reason for this is that the hormone levels present in these therapies do not appear to promote fibroid development or growth in most women (similarly, research suggests that hormone replacement therapy for menopause symptoms does not appear to increase uterine fibroid size in most women).

However, even if estrogen and progesterone are not used as a primary treatment method for uterine fibroid symptoms, they can be used to compensate for the effects of other uterine fibroid treatments. For example, gonadotropin-releasing hormone (Gn-RH) agonists may be used to stop fibroid growth or shrink fibroids by inhibiting estrogen production in the ovaries. While Gn-RH agonist treatment can be highly successful, it medically induces menopause for the duration of treatment and can bring with it a host of menopause symptoms, such as hot flashes, and cause bone loss, making it most appropriate for short-term use prior to surgery. To counter these effects, you and your practitioner may decide to use estrogen as an add-back therapy, which can allow you to experience the benefits of Gn-RH agonist treatment in a more safe and tolerable way. The same is true for women using an aromatase inhibitor to treat uterine fibroids. 

Estrogen replacement therapy is also invaluable following hysterectomy that includes removal of the ovaries. This treatment results in surgically-induced menopause, which can produce a wide range of sudden, severe physical and emotional menopause symptoms while also significantly increasing your risk of certain health conditions, including osteoporosis. Hormone replacement therapy after hysterectomy can help you re-establish balance in the short term and protect your long-term well-being.

Finding Relief from Uterine Fibroids

Living with uterine fibroids can be difficult—even if you don’t know you have them. If you are experiencing symptoms of fibroids, it’s important to reach out for help to ensure proper diagnosis and personalized treatment. For many women, connecting with a hormone health specialist is a particularly vital step in the journey towards healing. With their guidance, you can ensure that you have access to the most advanced treatment options available, including custom hormone replacement therapy, whether for primary, add-back, or post-surgical treatment. They can also help you implement any lifestyle changes needed to reduce symptoms, promote hormone balance, and enhance your overall well-being. 

With the right diagnosis and the right care, you can find relief from your symptoms and feel like yourself again—now and in the future.

If you think you may have uterine fibroids, BodyLogicMD can help. Practitioners in the BodyLogicMD network are experts in hormone health and committed to optimizing your health using the most innovative techniques available. By partnering with a BodyLogicMD-affiliated practitioner, you can address your symptoms and enhance your quality of life in a way that makes sense for you. Contact a local practitioner in your area to start your journey, or take the BodyLogicMD Hormone Balance Quiz to learn more about how hormones are impacting your everyday life.

Disclaimer: These statements have not been evaluated by the Food and Drug Administration. All content on this website is for informational purposes only. The content is not intended to diagnose, treat, cure or prevent diseases.


  • Charlotte

    Charlotte is a patient care coordinator specializing in bioidentical hormone replacement therapy. She is committed to helping patients who struggle with the symptoms of hormonal change and imbalance explore their treatment options and develop effective strategies to optimize wellness.