Abnormal bleeding from the uterus not related to menstruation .
Most common in the first few years after menarche and as menopause approaches, it is thought to occur when malfunctioning ovaries reduce blood estrogen levels. A malfunctioning hypothalamus or pituitary gland may also cause hormonally induced uterine bleeding, as can birth-control pills or hormone-replacement therapy. Some tumours produce estrogen and can alter the menstrual cycle, causing bleeding. Tumours in the uterus often bleed easily. Other causes include injury to the uterus, stress, obesity, chronic illness, psychological problems, and blood and cardiovascular disorders. Treatment is directed toward the underlying cause.