Fibroids are benign tumors that develop in the womb. The terms that are also used for fibroids are uterine myomas, fibromyomas or leiomyomas. Over 30 percent of women have fibroids and some of them don’t even know it. Fibroids are located on the uterine wall and they stay there, without any danger that they will move outward. The number of fibroids can vary, but most commonly that number is from four to seven. Fibroids can be intramural, subserosal, sub mucosal and pedunculated. Fibroids can be very small, but they can also grow up to 20 cm wide. Estrogen is the hormone that increases the chances for fibroid growth. In women who are in their menopause and have low level of estrogen fibroids getsmaller. During the pregnancy, fibroids can even become smaller. However, there are some fibroids such as sub mucosal, which can affect the possibility of staying pregnant. Fibroids rarely cause miscarriage, premature birth or bleeding. If you have fibroids during pregnancy, consult your doctor. The cases where fibroids are transforming into cancer are very rare.