Uterine fibroids are noncancerous growths that develop in or on the muscular walls of the uterus. Many women have uterine fibroids sometime during their lives, but most women don’t know they have them because the growths often cause no symptoms.
When fibroids do cause symptoms, they may include:
- Heavy menstrual bleeding
- Prolonged menstrual periods — lasting more than a week
- Pelvic pressure or pain
- Frequent urination
- Difficulty emptying the bladder
- Constipation
- Backache or leg pains
- Reproductive problems, such as infertility, multiple miscarriages or early labor
While researchers don’t know the exact cause of fibroids, they’ve identified factors and conditions that can influence cell growth and tissue function, which may impact fibroid development and growth. Understanding what triggers fibroid growth may help guide treatment and prevention strategies.
Hormones
Hormones appear to promote the growth of fibroids. Estrogen and progesterone, two hormones involved in the female reproductive cycle, promote the growth of uterine muscle cells, including fibroids. Fibroids contain higher levels of estrogen and progesterone receptors than normal uterine muscle cells.
The growth of fibroids appears to be tied to estrogen. Fibroids rarely develop before a woman’s first period and shrink after menopause, when estrogen levels decrease dramatically. Women who take hormone therapy after menopause, especially estrogen alone, are more likely to develop fibroids.
Birth control pills and other methods of contraception that contain estrogen also may promote the growth of fibroids. Pregnancy provides a temporary reprieve from fibroid growth, with many fibroids shrinking at the end of each pregnancy. That’s because levels of estrogen and progesterone decline dramatically after giving birth.
Family history and genetics
If you have a mother, sister or daughter with uterine fibroids, you’re at increased risk of developing fibroids yourself. Many women who have fibroids have a family history of the noncancerous tumors. More research is needed, but having a genetic predisposition may contribute to fibroid development.
Race
Uterine fibroids are most common in women in their 30s and 40s, but they can occur at any age. In general, African American women are more likely to develop fibroids than Caucasian women. In addition, African American women tend to develop fibroids at a younger age, and the tumors seem to grow more quickly.
Obesity
Excess body weight is a risk factor for fibroids. This may be related to increased estrogen levels in heavier women. New research suggests a link between vitamin D deficiency and increased risk of uterine fibroids, especially in overweight and obese women.
Other factors
Other factors that can promote the development and growth of fibroids include:
- High blood pressure
- Drinking alcohol, especially beer
- Eating more red meat and ham
- Having an early first menstrual cycle before age 10
- Never giving birth
Some researchers think fibroids may be more common in women who have never been pregnant. The exact reason for this is unclear, but could be related to pregnancy helping decrease estrogen and progesterone levels.
What triggers the growth of fibroids?
Researchers don’t know exactly why fibroids form. Most believe that fibroid growth is tied to hormone levels, especially estrogen. Estrogen and progesterone promote the growth of uterine muscles cells. The following factors can influence hormone levels and promote fibroid growth:
- Genetics. If your mother or sister has fibroids, you’re at increased risk.
- Ethnicity. Fibroids are more common in African American women.
- Overweight/obesity. Excess fat tissue increases estrogen levels.
- Early first period. Beginning periods early, before age 10, increases lifetime exposure to estrogen.
- Pregnancy. Pregnancy reduces risk, possibly by decreasing estrogen levels.
- Oral contraceptives. Birth control pills appear to promote the growth of fibroids.
- Perimenopause. Estrogen levels fluctuate and decline during the years leading up to menopause.
- Hormone therapy. Estrogen prescribed after menopause may increase the risk of new fibroids.
Uterine fibroids are hormone-sensitive tumors. They contain more estrogen and progesterone receptors than normal uterine muscle cells. The hormones estrogen and progesterone promote the growth of uterine muscles cells, including fibroids.
African American women are two to three times more likely to develop fibroids than Caucasian women. In addition, African American women tend to get fibroids at a younger age and have more symptoms when the tumors are small. Researchers think genetics and hormonal factors may play a role in the racial differences.
Having an early first menstrual cycle, before the age of 10, increases lifetime exposure to estrogen. Women who started menstruating early are at increased risk of fibroids compared to those who had their first period after age 10.
Pregnancy appears to protect against fibroids. They’re less common in women who’ve had children. Researchers think pregnancy reduces the risk by decreasing estrogen and progesterone levels. After pregnancy, estrogen and progesterone levels remain low while breastfeeding continues.
Women taking oral contraceptives, such as birth control pills, appear to have an increased risk of fibroids. Some studies find that oral contraceptives increase the size and number of fibroids in women who already have the tumors. Researchers think birth control pills increase estrogen levels and promote the growth of fibroids.
Obesity increases the risk of uterine fibroids. Excess body fat leads to higher levels of estrogen. Overweight and obese women produce more estrogen in their fat tissue. Losing weight may help ease symptoms of uterine fibroids.
Perimenopause refers to the years leading up to menopause when estrogen levels fluctuate and gradually decline. Changing hormone levels during perimenopause and menopause may cause fibroids to grow. Women nearing menopause are often diagnosed with uterine fibroids as the tumors grow and create symptoms.
Conclusion
Uterine fibroids are hormone-sensitive tumors that are affected by the female hormones estrogen and progesterone. Genetics likely make some women more prone to developing fibroids than others. Estrogen appears to promote the growth of fibroids through various mechanisms.
Being overweight or obese also increases risk, possibly by increasing estrogen levels. Having an early first period and never giving birth appear to increase lifetime exposure to estrogen. Using oral contraceptives and taking hormone therapy after menopause also may influence fibroid growth.
While fibroids tend to shrink after menopause, when estrogen levels decline, factors that increase overall lifetime exposure to estrogen seem to stimulate the growth of these common, noncancerous tumors.
Understanding what triggers the development and growth of fibroids can help guide treatment and prevention strategies. Maintaining a healthy weight, exercising regularly, eating nutritious foods, and avoiding excess alcohol may help balance hormone levels and prevent problems with uterine fibroids.
Frequently Asked Questions
Are fibroids genetic?
Research suggests genetics play a role in fibroid development. Having a mother, sister or daughter with uterine fibroids increases your risk. Estimates range widely, but studies indicate if you have a first-degree female relative with fibroids, your risk may be 2-3 times higher.
Do fibroids run in families?
Yes, there appears to be a familial predisposition to developing uterine fibroids. If your mother, sister or daughter has fibroids, you’re at increased risk. Genetics likely make some women more prone to fibroids than others.
Can birth control cause fibroids to grow?
Some research suggests birth control pills containing estrogen may promote the growth of existing fibroids. Oral contraceptives increase circulating estrogen levels in the body. Since fibroids are estrogen-sensitive, the hormones may cause them to grow larger.
Does having fibroids make it harder to get pregnant?
In most cases, small fibroids don’t affect pregnancy. But larger or multiple fibroids inside the uterus cavity can impair fertility and increase the risks of infertility, miscarriage and premature labor.
Can Apple cider vinegar shrink fibroids?
There isn’t solid scientific evidence that apple cider vinegar can shrink fibroids. Small studies show it may provide some benefits for excess postmenstrual bleeding, but more research is needed. Avoid applying undiluted vinegar directly to the skin.
What vitamins should I take to shrink fibroids?
No vitamin or supplement has been proven to effectively shrink fibroids. Maintaining adequate vitamin D levels may help. Make sure you get 600 IU of vitamin D daily. Eating foods rich in vitamin A, vitamin C and magnesium also may help regulate estrogen.
Do uterine fibroids go away after menopause?
After menopause, when estrogen levels decrease significantly, fibroids often shrink or disappear. But it’s possible for fibroids to persist after menopause. Large fibroids may continue causing symptoms that require treatment.
Can losing weight help shrink fibroids?
There isn’t enough research to prove that weight loss alone can shrink fibroids. However, maintaining a healthy weight may help keep estrogen levels in balance. Losing excess body fat reduces estrogen production.
Can progesterone cream shrink fibroids?
Using progesterone creams hasn’t been proven effective for shrinking fibroids. Progesterone promotes growth of uterine muscles, including fibroids. Oral or injected progesterone often shrinks fibroids, but the creams may not adequately reach the uterine tissue.
How fast can fibroids grow back after surgery?
After myomectomy to remove fibroids, regrowth rates range from 3% to 60%. Factors like number, size and location impact regrowth. Recurrence after hysterectomy is rare. Lifestyle changes and medications may help prevent new fibroids.
Key Takeaways
- Estrogen appears to promote the growth of fibroids, which contain more estrogen receptors than normal uterine cells.
- Genetics likely make some women more prone to developing fibroids.
- Being overweight and obese increases estrogen levels and fibroid risk.
- Oral contraceptives may increase the risk of new fibroids.
- Pregnancy and breastfeeding reduce risk by decreasing estrogen levels.
- Fibroids often shrink after menopause when estrogen levels drop.