In many women, a hormone imbalance causes bleeding. These women may have too much estrogen or not enough progesterone. Polyps or fibroids (small and large growths) in the uterus can also cause bleeding. Cancer of the uterus and infection of the cervix are other causes of bleeding. Sometimes a thyroid problem causes bleeding. Below you may find medications used to treat or help with Abnormal Uterine Bleeding. More about Abnormal Uterine Bleeding