Although they can occur at any age, fibroids are most likely to occur in women aged 30-40 and are found in black women more often than white women. In black women, fibroids seem to occur at a younger age and grow more quickly. Also called leiomyomas or myomas, uterine fibroids develop from cells that make up the muscle of the uterus. Fibroids may vary in size, shape and location. Some fibroids have gotten large enough to completely fill the pelvis or abdomen.
Fibroids can be difficult to treat because the way in which they occur is unpredictable.
They can appear alone or in groups, grow slowly or very rapidly. Although quite common, their cause is somewhat a mystery. Estrogen , the essential female hormone, seems to increase their growth. Estrogen levels can change as a woman's body changes or with medications being taken. Even large fibroids may produce no symptoms.