When these cells go awry, however, they develop into a clump within the myometrium, the smooth muscle coat of the uterus, which forms the main part of the organ. Fibroid tumors are therefore a collection of innocent uterine muscle cells that form a noticeable hard lump. Fibroids develop most commonly in women who are in their thirties and forties, but they can also develop earlier or later than this. In fact, about 30 percent of all women will develop fibroids by the time they reach thirty-five, and fibroids are more common in black women. An estimated 20 percent of white women and 50 percent of black women over thirty years old have fibroids.
Fibroids are grayish white, firm, round, and ring-shaped.
They come in all sizes, and it's common to have several fibroids growing at once. The main problem is that once fibroids develop, they may continue to grow, and even if they're surgically removed, there's a 10 percent chance they'll grow back. This is the main reason why so many doctors recommend hysterectomies for women with fibroids. Nobody knows why fibroids develop. What we do know is that estrogen can trigger fibroids and may make the fibroids grow more quickly.