context: From conception to delivery, a woman's uterus can grow from the size of a pear to the size of a watermelon. But pregnancy isn't the only potential reason for an enlarged uterus. An enlarged uterus is common and can be a symptom of a variety of medical conditions, some of which require treatment. Two of the most common causes of an enlarged uterus are uterine fibroids and adenomyosis. Uterine fibroids. Uterine fibroids are common noncancerous tumors of the muscular wall of the uterus, affecting as many as eight in 10 women by the age of 50. Fibroids more commonly affect women over age 30. They are also more common in African- Americans than Caucasians. Overweight and obese women also have a greater risk of developing fibroids. Hormonal and genetic factors contribute to their growth. While some fibroids are very small, others grow to weigh several pounds. A woman may have a single fibroid or multiple fibroids. In addition to an enlarged uterus, symptoms of uterine fibroids may include: Feeling of fullness or pressure in the lower abdomen Heavy, painful, and/or long-lasting periods, sometimes with the passage of blood clots Bleeding between periods Constipation Frequent urination Pain during intercourse Pregnancy or delivery complications If symptoms are severe, treatment may involve a procedure called uterine artery embolization to cut off the blood supply to the fibroids so that they shrink and eventually die, or surgery to remove the fibroids (myomectomy) or the entire uterus (hysterectomy). Other treatments include endometrial ablation. This procedure is performed for small submucusal fibroids (when the inside lining of the uterus is removed, burned or frozen) and laparoscopic myolysis (when freezing or an electric current is used to destroy the fibroids). Medications to help control painful periods or for pain may also be used. Other treatment options include focused ultrasound surgery and an intrauterine device ( IUD) to decrease bleeding. The cause of fibroids is not known, but the tumors seem to rely on estrogen to grow. After menopause, they often shrink naturally and cause no symptoms. Adenomyosis. Adenomyosis is a diffuse thickening of the uterus that occurs when the tissue that normally lines the uterus (endometrium) moves into its muscular outer wall and behaves like the endometrium. When this happens in a small area, or is localized, it is called an adenomyoma. While the cause of adenomyosis is unknown, the condition usually occurs in women older than age 30 who have had children. It is more common in women who have had uterine surgery, including a cesarean section. In addition to uterine enlargement, symptoms may include: Long periods or heavy bleeding Painful periods, which get continually worse Pain during intercourse Most women have some adenomyosis at the end of their childbearing years. Most don't require treatment, but some need medication to relieve pain. Birth control pills and an intrauterine device ( IUD) containing progesterone may help decrease heavy bleeding. Women with severe symptoms may need a hysterectomy to relieve symptoms. In some cases, an enlarged uterus can be a symptom of uterine cancers, including endometrial cancer (affecting the lining of the uterus) and cervical cancer (affecting the lower portion of the uterus where it joins the vagina). Treatment depends on the location, the extent of the cancer, and other factors. If you have an enlarged uterus, you won't necessarily notice it yourself. Your doctor may discover it during a physical exam or on imaging tests. Many conditions that cause an enlarged uterus are benign and don't require treatment unless symptoms are severe. If you experience problems such as irregular bleeding; painful, heavy periods; pain during intercourse; or feelings of fullness or pressure in the lower abdomen, see your doctor, who can help determine the cause and best treatment.