What are Uterine Fibroids?

Did you know that uterine fibroids don't often present with obvious symptoms and many people assigned female at birth (AFAB) can go undiagnosed with them? Uterine fibroids, however, are fairly common in people between the ages of 30 and 50, when oestrogen and progesterone levels (female reproductive hormones) are at their highest. 

Also known as uterine myomas or leiomyomas, uterine fibroids are non-cancerous growths that can appear inside or outside the uterus. These growths can range in size and are composed of muscle and fibrous tissues.1 This article will take a closer look into the causes, signs and management of uterine fibroids.


Uterine fibroids can develop inside the uterus's muscular wall and can often go undiagnosed. Up to 80% of people AFAB will be affected by the age of 50, making uterine fibroids the most prevalent type of uterine growth. Uterine fibroids can range in size from pea-sized nodules (small lumps) to large tumours that can change the structure of the uterus. Although the majority of women with fibroids do not experience symptoms, some women with fibroids report abnormally heavy or prolonged menstrual flow, pelvic pressure or pain, urinary incontinence, and infertility.1

The main types of uterine fibroids are:

  • Intramural fibroids: Form in the uterine muscular wall
  • Submucosal fibroids: Form in the muscle layer beneath the lining of the womb and grow into the cavity of the womb
  • Subserosal fibroids: Develop outside the wall of the womb into the pelvis and can grow to be quite large

Causes of uterine fibroids

The specific cause of uterine fibroids is uncertain but it is believed that oestrogen hormone levels and genetic abnormalities in the smooth muscle cells of the uterus could be responsible. 

Risk factors that have been linked to developing uterine fibroids are:

  • Age: People AFAB aged between 30-50 have a higher incidence of developing fibroids
  • Genetics: People AFAB with a family history of uterine fibroids may have a higher chance of experiencing them2
  • Hormonal influences: The likelihood of having fibroids is higher in people AFAB who have never given birth, who started menstruating early, and who have longer monthly bleeding. The likelihood decreases in those who have had children but increases during pregnancy when hormone levels are high. Uterine fibroids are likely to shrink after menopause when the hormones oestrogen and progesterone are at their lowest level2
  • Obesity: There is an increased likelihood of developing fibroids if you are obese. A high body mass can contribute to raised oestrogen levels
  • Ethnicity: African Caribbean people are more at risk of developing fibroids than those from other ethnicities3
  • Diet: A diet high in red meat and low in fruits and vegetables has been found to raise the incidence of uterine fibroids. However, more research is required on the dietary factors that may affect and cause uterine fibroids4

Signs and symptoms of uterine fibroids

Depending on the size and location of the fibroids, the signs and symptoms of uterine fibroids can be different. While some might not experience symptoms, others might experience severe symptoms that could significantly impact their quality of life. Some signs and symptoms include:5

  • Painful periods and a heavy menstrual flow which can cause anaemia 
  • Pain or discomfort during sexual activity 
  • Lower back pain
  • Pelvic pain and a feeling of weight or pressure in the pelvic area
  • Urinary frequency or urgency can be brought on by fibroids pressing on the bladder, which can also make it difficult to empty the bladder
  • Constipation as fibroids can press on the rectum, making it hard to pass faeces 
  • Infertility or recurrent miscarriages if fibroids restrict the fallopian tubes or prevent a fertilised egg from implanting properly

Management and treatment for uterine fibroids

If you have uterine fibroids but no symptoms or only minimal symptoms that do not significantly interfere with your daily activities, treatment may not be required. However, it is advisable to see your doctor or gynaecologist to monitor your fibroid growth and symptoms and address any concerns. Based on the size, location, and severity of the symptoms, there are several management and treatment options for fibroids:

  • Medications: To reduce heavy periods or manage pain
    • Progestins, oral contraceptives, and GnRH agonists are examples of hormonal drugs that can be used to treat symptoms of fibroids such as excessive bleeding and pain. These drugs function by controlling the hormones that affect fibroid growth6
    • Non-steroidal anti-inflammatory drugs (NSAIDs): Such as naproxen and ibuprofen, can be prescribed as a non-hormone alternative to reducing pain and managing symptoms
  • Levonorgestrel intrauterine system (LNG-IUS): Also known as the Mirena coil, can be used to manage symptoms associated with uterine fibroids. The LNG-IUS device is a small, T-shaped piece of plastic that is implanted in your womb and releases levonorgestrel, which is a progestogen hormone. This device prevents the lining of your womb from expanding quickly, making it thinner and causing lighter bleeding
  • Surgery: An alternative if medication or the coil is unsuitable. For fibroids, the two main surgical procedures are myomectomy and hysterectomy. While a hysterectomy requires removing the entire uterus, a myomectomy only requires removing the fibroids from the walls of the uterus. Based on the severity of symptoms, your doctor will help you determine the best course of treatment
  • Non-invasive surgical methods: This includes uterine artery embolisation (UAE) which involves blocking the blood supply to the fibroids, causing them to shrink. Endometrial ablation can also be carried out which is the removal of the womb lining using a laser or a heated wire loop. These procedures can be carried out under general anaesthesia

Diagnosis of uterine fibroids

During a pelvic examination, your doctor may be able to look for obvious signs of fibroids and refer you for further tests to confirm the diagnosis. They may enquire about symptoms such as severe menstrual bleeding, pressure, and pain in the pelvis. They will ask about any prior fibroid diagnosis, family history, and other health issues that may have an impact on the uterus. 

An ultrasound is usually the main test for diagnosis, used to confirm the presence of fibroids and to get a closer look at the size and location of fibroids. 

In some cases, hysteroscopy and laparoscopy may need to be carried out to confirm the presence of uterine fibroids when the ultrasound and other tests fail to confirm the diagnosis. 


Although uterine fibroids are non-cancerous, some complications can arise depending on the size and location of fibroids. Large fibroids can cause fertility complications such as:

  • Preventing the fertilised egg from implanting
  • Preventing the development of the foetus during pregnancy which can result in preterm labour, pregnancy issues and in rare cases, miscarriage
  • C-section (caesarean) due to fibroid blocking the vagina


How can I prevent uterine fibroids?

Unfortunately, you can’t prevent uterine fibroids, however, you can reduce the risk. Maintaining a healthy weight and lifestyle, a healthy diet and regular pelvic examinations and gynaecology check-ups can reduce the risk of fibroids. 

How common are uterine fibroids?

Uterine fibroids are fairly common in people AFAB aged between 30-50 however, a lot of women may never be diagnosed as they experience mild to very few symptoms. 

Where do fibroids grow?

Fibroids can grow anywhere on the uterine muscular wall, outside the wall of the uterus or within the cavity of the uterus. 

When should I see a doctor?

You should see a doctor or seek medical attention if you are experiencing heavy menstrual bleeding, pelvic pain or notice abdomen enlargement. 


Uterine fibroids are common in people assigned female at birth, aged 30-50, or during their reproductive years; however, not all women will experience symptoms. Symptoms include heavy menstrual bleeding, pelvic pain, period pains, frequent urination and in some cases, difficulty getting pregnant. Regular gynaecology checks can help detect fibroids early and prevent complications, leading to a better quality of life. 


  1. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 200: Uterine Fibroids. Obstetrics and Gynecology. 2018; 131(4): 87-100.
  2. Stewart E A, Laughlin-Tommaso S K, Catherino W H, Lalitkumar S. Uterine Fibroids: Pathogenesis and Interactions with Endometrium and Endomyometrial Junction. Obstet Gynecol Clin North Am. 2019;46(3):407-421.
  3. Baird D D, Dunson D B, Hill M C, et al. High cumulative incidence of uterine leiomyoma in black and white women: ultrasound evidence. Am J Obstet Gynecol. 2003;188(1):100-107.
  4. Wise L A, Radin R G, Palmer J R, et al. A prospective study of dairy intake and risk of uterine leiomyomata. Am J Epidemiol. 2010;171(2):221-232.
  5. Marsh E E, Al-Hendy A, Kappus D, Galitsky A, Stewart E A. An evidence-based approach to the medical management of fibroids: a systematic review. Clin Obstet Gynecol. 2016;59(1):30-52.
  6. Schlaff W D. Current management of uterine fibroids. Obstet Gynecol. 2014;124(2 Pt 1):428-43.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Sabiya Ali

BSc Pharmacy Science and Health University of the West of Scotland

Hi, my name is Sabiya and I am currently a recent graduate. I am passionate about science and particularly interested in women's health. I enjoy researching and writing articles which is why I decided to work for Klarity's public health library.

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