Fibroids

Uterine fibroids are noncancerous growths of the uterus that often appear during childbearing years. Also called leiomyomas (lie-o-my-O-muhs) or myomas, uterine fibroids aren't associated with an increased risk of uterine cancer and almost never develop into cancer.
Fibroids range in size from seedlings, undetectable by the human eye, to bulky masses that can distort and enlarge the uterus. You can have a single fibroid or multiple ones. In extreme cases, multiple fibroids can expand the uterus so much that it reaches the rib cage and can add weight.
Many women have uterine fibroids sometime during their lives. But you might not know you have uterine fibroids because they often cause no symptoms. Your doctor may discover fibroids incidentally during a pelvic exam or prenatal ultrasound.

Symptoms

Many women who have fibroids don't have any symptoms. In those that do, symptoms can be influenced by the location, size and number of fibroids.
In women who have symptoms, the most common signs and symptoms of uterine fibroids include:

• Heavy menstrual bleeding
• Menstrual periods lasting more than a week
• Pelvic pressure or pain
• Frequent urination
• Difficulty emptying the bladder
• Constipation
• Backache or leg pains

Causes

Doctors don't know the cause of uterine fibroids, but research and clinical experience point to these factors:

• Genetic changes. Many fibroids contain changes in genes that differ from those in typical uterine muscle cells.
• Hormones. Estrogen and progesterone, two hormones that stimulate development of the uterine lining during each menstrual cycle in preparation for pregnancy, appear to promote the growth of fibroids.
• Other growth factors. Substances that help the body maintain tissues, such as insulin-like growth factor, may affect fibroid growth.
• Extracellular matrix (ECM). ECM is the material that makes cells stick together, like mortar between bricks. ECM is increased in fibroids and makes them fibrous. ECM also stores growth factors and causes biologic changes in the cells themselves.

Risk factors

There are few known risk factors for uterine fibroids, other than being a woman of reproductive age. Factors that can have an impact on fibroid development include:

• Race. Although all women of reproductive age could develop fibroids, black women are more likely to have fibroids than are women of other racial groups. In addition, black women have fibroids at younger ages, and they're also likely to have more or larger fibroids, along with more-severe symptoms.
• Heredity. If your mother or sister had fibroids, you're at increased risk of developing them.
• Other factors. Starting your period at an early age; obesity; a vitamin D deficiency; having a diet higher in red meat and lower in green vegetables, fruit and dairy; and drinking alcohol, including beer, appear to increase your risk of developing fibroids.

Pregnancy and fibroids

Fibroids usually don't interfere with getting pregnant. However, it's possible that fibroids — especially submucosal fibroids — could cause infertility or pregnancy loss.
Fibroids may also raise the risk of certain pregnancy complications, such as placental abruption, fetal growth restriction and preterm delivery.