pelvisawareness_adminPolyps & Fibroids

What Causes Uterine Fibroids To Grow?

If you have heavy menstrual bleeding or periods that last more than a week, you may have uterine fibroids. 

You could also have fibroids and not know, because there may be no symptoms whatsoever.

Women who have this condition, or know someone affected, often ask: what causes uterine fibroids to grow? Let’s find out.

Understanding Uterine Fibroids

Uterine fibroids—also called myomas or leiomyomas—are noncancerous growths of the uterus. They often appear during childbearing years, and almost never develop into cancer.1

While some women don’t have any symptoms, some women suffer from heavy menstrual bleeding or menstrual periods lasting more than a week. Other side effects include pelvic pressure or pain, frequent urination and difficulty emptying the bladder, constipation and backache or leg pains.1 Some women suffer from pain during sex.2

What Causes Uterine Fibroids To Grow

Fibroids range in size, too. They can be as small as a grain of rice or grow as big as a melon, and you could have one or many fibroids. They may grow into the uterine cavity or outward from the uterus on stalks.3

If you have fibroids, you aren’t alone. Some estimates put the number at 40 to 80% of people who have fibroids.2 Others estimate that 20% to 50% of women of reproductive age currently have fibroids, and up to 77% of women will develop fibroids sometime during their childbearing years.3

But what causes fibroids to grow? The exact cause isn’t known. The hormone estrogen may play a part. Some research suggests that a fibroid develops from an abnormal muscle cell in the uterus, and when estrogen is present, it causes the tumor to grow.3

There are some risk factors that have been identified. It seems that these factors may play a role in the development of fibroids:

  • a family history of fibroids2
  • obesity or a higher body weight2
  • not having children2
  • getting your period at a young age2
  • late age for menopause2
  • a diet high in red meat3
  • high blood pressure3

Research and clinical experience also indicate these possible causes:

1. Genetic changes: Some fibroids contain changes in genes that differ from those in typical uterine muscle cells.1

2. Hormones: The two hormones that stimulate development of the uterine lining during each menstrual cycle—estrogen and progesterone—appear to promote the growth of fibroids.1

3. Other growth factors: Other substances that help the body maintain tissues may affect fibroid growth.1

As well, black women are more likely to develop fibroids than other women. It’s not understood why, but they are also diagnosed at younger ages and they more often require treatment.3

As for treatment, the location and size impact the treatment plan. Fibroids can grow inside or outside your uterus, and in different places. Your doctor will examine where they are growing, how big they are and how many of them you have before determining a treatment plan. Larger fibroids can be treated with medications or surgery, while small ones often require no treatment.2

See a Doctor 

If you have one or more symptoms of uterine fibroids, use our Physician Finder to find a doctor near you with expertise in women’s health, for proper diagnosis and treatment. In particular, see a doctor if you have pelvic pain that doesn’t go away; overly heavy, prolonged or painful periods, or spotting between periods; or difficulty emptying your bladder. Seek medical attention immediately if you have severe vaginal bleeding or sharp pelvic pain that comes on suddenly.1