Gillian Goddard

6 minute read Gillian Goddard

Gillian Goddard

All About Fibroids

What they are, and how they’re related to estrogen

Gillian Goddard

6 minute read

A patient came to me for a consultation regarding her heavy and irregular periods. She had an appointment with her gynecologist coming up, but she was concerned that her frequent vaginal bleeding might be related to her underactive thyroid. When her blood work came back, her thyroid levels looked fine, but she told me her gynecologist had diagnosed her with fibroids.

We were discussing the possibility of birth control pills to control her bleeding symptoms. She was interested, but she had one specific reservation. She had read that birth control pills might cause her fibroids to grow. She was really hoping to avoid surgery, so she wanted to avoid anything that might necessitate it. We discussed her concerns. Given how common fibroids are, it seems likely some of you might have the same concerns.

What are fibroids?

Fibroids are benign tumors that grow from the muscle cells that make up the walls of the uterus. They are exceedingly common. In one study, a group of women between the ages of 35 and 49 were randomly selected to determine whether or not they had fibroids based on medical records and an ultrasound of the uterus. Among this group of more than 1,300 women, it was estimated that 80% of Black women and nearly 70% of white women develop fibroids by age 50.

While many women will not have symptoms from their fibroids, those who do experience symptoms report pelvic pain, heavy uterine bleeding, and urinary and bowel issues. Often symptoms can adversely affect a woman’s daily functioning and need to be addressed. In some cases, depending on their size and location, fibroids can impact fertility. In rare cases, fibroids have been found to make hormones such as prolactin, which triggers breast milk production, and parathyroid hormone, which controls calcium levels in the blood and bones. Those hormones could circulate in the blood, causing symptoms like breast discharge or high calcium levels.  

Panuwat Dangsungnoen / Getty

What causes fibroids to increase (or decrease) in size?

Researchers have long been interested in understanding what causes fibroids to grow. Because fibroids appear during the reproductive years and often decrease in size after menopause, it is reasonable to hypothesize that their growth is driven by hormones. In fact, fibroids are considered to be estrogen-dependent, meaning they need estrogen to grow. We also know that fibroid cells have estrogen receptors. Girls who have their first menstrual period before age 10 are also more likely to develop fibroids later in life, likely due to increased exposure to estrogen over their reproductive lifetime. 

Does it follow that taking estrogen will cause fibroids to grow? There is a great deal of conflicting evidence regarding estrogen’s effects on fibroid size. A number of studies (for example, here, here, and here) have shown that birth control pills with less than 36 micrograms of ethinyl estradiol (virtually all pills on the market today) do not cause fibroids to increase or decrease in size. 

What about hormone therapy for perimenopausal symptoms? There is conflicting data. Studies like this one suggest that hormone therapy leads to a statistically significant increase in fibroid volume in the first two years of use but not at three years of use. Ultimately, for many women the benefits of treating their intrusive perimenopausal symptoms will outweigh the risk of increasing the volume of their fibroids. Having fibroids, even symptomatic ones, is not a contraindication to taking hormone therapy for perimenopausal symptoms.

What treatments are available?

Fibroids are benign. If you have them and they aren’t bothering you, there is nothing to do. They will likely shrink and be even less likely to cause trouble after menopause. However, if they are causing pain or heavy bleeding that is affecting your functioning, they need to be addressed. How symptoms are managed depends on what types of symptoms a woman is experiencing and her age. Because fibroid symptoms typically improve after menopause, if a woman is perimenopausal, the goal of treatment is to manage symptoms until they improve on their own with menopause. 

Heavy uterine bleeding

Heavy bleeding from fibroids can get worse in the perimenopausal years, but there are a number of options for managing it. For women in the late-reproductive stage and early perimenopause, birth control pills that contain both estrogen and progesterone can be an excellent option. They not only reduce uterine bleeding — or eliminate it completely if the sugar pills that make up the last four to seven pills in the pack are skipped — but can treat any symptoms of perimenopause a woman might be experiencing and provide effective contraception if needed.

Progestin-eluting IUDs, such as Mirena, can also be an effective choice. While they won’t manage perimenopausal symptoms like hot flushes or night sweats, IUDs can reduce or even eliminate bleeding and provide effective contraception. They are especially useful for women who cannot take estrogen.

In some cases, the best option is to remove the fibroid. Particularly if it protrudes into the uterus, a surgeon can insert a camera through the cervix into the uterus, see the fibroid, and remove it with instruments inserted through a hollow portion of the camera. 

Pain

For women experiencing pain or pressure from fibroids, the treatment options are often different. Leuprolide, a medication that shuts down the entire reproductive hormone signal from the brain to the pituitary gland to the ovaries, has been shown to reduce the size of fibroids. However, because it lowers estrogen levels essentially to zero, it can cause a lot of perimenopausal symptoms. 

A procedure called uterine artery embolization can also reduce the size of and pain due to fibroids. It involves inserting a catheter into the artery that supplies blood to the uterus, usually via an artery in the groin, and injecting a substance that blocks the artery, cutting off the blood flow. Patients can experience pain after the procedure, but this is typically limited. Uterine artery embolization has been shown to reduce pressure and pain in up to 80% of cases. 

In severe cases of fibroids causing pain or heavy bleeding, the best option may be surgery to remove either the fibroids (myomectomy) or the entire uterus (hysterectomy). Decisions about myomectomy and hysterectomy should be given careful consideration in consultation with your doctor. 

The bottom line

  • Fibroids are benign growths that stem from the muscle cells that make up the wall of the uterus. 
  • They are exceedingly common, but not all women with fibroids have symptoms.
  • Though fibroids are estrogen-dependent, it is not clear whether taking estrogen as hormone therapy causes significant growth in fibroids, and fibroids are not a contraindication to taking hormone therapy for perimenopausal symptoms. 
  • Symptomatic fibroids can be treated medically or surgically depending on the types of symptoms a woman is experiencing and her age. 
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