Most women will develop uterine fibroids at some point in their lives, particularly during their childbearing years, but doctors have not pinpointed what causes them.

Fibroids develop and grow from the walls of the uterus, or womb. Also called leiomyomas or myomas, they consist of smooth muscle cells and fibrous connective tissue. They range in size from undetectable to enlarged masses that, in extreme cases, cause bloating and distension of the stomach. Fibroids may occur as a single tumor or in clusters that vary in size and shape and may grow. What’s more, they may shrink or remain the same size over time. Nearly 80% of Black women and 70% of white women are likely to develop fibroids by age 50.

“Women trying to understand their risk of developing fibroids—and their options if they’re diagnosed—are often thwarted by misinformation circulating about this potentially confusing condition,” explains Kecia Gaither, MD, MPH, a board-certified ob-gyn and maternal fetal medicine physician. “It’s crucial to set the record straight about fibroid facts versus fiction.”

Fibroids react to estrogen levels in a woman’s body. For example, during pregnancy, large amounts of the hormone can prompt tumors to grow. Conversely, during menopause, when women produce less estrogen, fibroid volume tends to diminish. 

Fibroids are categorized by their location in the uterus. They include endometrial fibroids, which grow underneath the mucosal lining of the uterus and into the endometrial cavity; intramural fibroids, which are found between the muscles of the uterus; subserosal fibroids, which develop on the outside of the uterus; and pedunculated fibroids with stalks that project from the surface of the uterus into the uterine cavity.

Myth No. 1: Fibroids are cancerous growths.

Fact No. 1: Fibroids are most often benign, meaning noncancerous. They are often referred to as tumors, but a tumor is just abnormal tissue that is not necessarily cancerous.

Myth No. 2: Every woman with fibroids will experience symptoms.

Fact No 2: Not every woman experiences the common symptoms of fibroids, such as heavy menstrual bleeding, pain, pelvic pressure and frequent urination. Indeed, 50% to 80% of women with the condition have no symptoms, and many women with fibroids go undiagnosed.

Myth No. 3: Uterine fibroids result in infertility.

Fact No. 3: While fibroids can make getting pregnant difficult, women with the condition can have children. However, fibroids that block a fallopian tube or change the shape of the cervix can restrict the number of sperm allowed to enter the uterus, lowering a woman’s chances of becoming pregnant.

Myth No. 4: Only women in their 30s and 40s develop fibroids.

Fact No. 4: Women younger than 35 and those in their 50s can still develop fibroids.

Myth No. 5: Hysterectomy is the only effective treatment for fibroids.

Fact No. 5: Several minimally invasive treatment options are available to women with fibroids. Uterine fibroid embolization (UFE) cuts the flow of blood to fibroids. Magnetic resonance–guided high-intensity focused ultrasound is a newer method that zeroes in on fibroids and shrinks or destroys them. Finally, radiofrequency ablation uses high-energy waves to eliminate uterine fibroids.