Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Uterine Fibroids ?
    ### Response:
    Uterine fibroids are the most common benign tumors in women of childbearing age. Fibroids are made of muscle cells and other tissues that grow in and around the wall of the uterus, or womb. The cause of fibroids is unknown. Risk factors include being African American or being overweight.
    