What causes abnormal uterine bleeding?

Overview

Abnormal uterine bleeding is any bleeding from the uterus (through your vagina) other than your normal monthly period. Having extremely heavy bleeding during your period can also be considered abnormal uterine bleeding. Very heavy bleeding during a period and/or bleeding that lasts more than 7 days is called menorrhagia (say: “men-oh-raj-ee-ah”). Women who have menorrhagia may, for example, bleed enough to soak through 1 or more tampons or sanitary pads every hour.

Causes & Risk Factors

What causes abnormal uterine bleeding?

Many different things can cause abnormal uterine bleeding. Pregnancy is a common cause. Polyps or fibroids (small and large growths) in the uterus can also cause bleeding. Rarely, a thyroid problem, infection of the cervix or cancer of the uterus can cause abnormal uterine bleeding.

In most women, abnormal uterine bleeding is caused by a hormone imbalance. When hormones are the problem, doctors call the problem dysfunctional uterine bleeding, or DUB. Abnormal bleeding caused by hormone imbalance is more common in teenagers or in women who are approaching menopause.

These are just a few of the problems that can cause abnormal uterine bleeding. These problems can occur at any age, but the likely cause of abnormal uterine bleeding usually depends on your age.

Women in their teens, 20s and 30s

A common cause of abnormal bleeding in young women and teenagers is pregnancy. Many women have abnormal bleeding in the first few months of a normal pregnancy. Some birth control pills or the intrauterine device can also cause abnormal bleeding.

Some young women who have abnormal uterine bleeding do not release an egg from their ovaries (called ovulation) during their menstrual cycle. This is common for teenagers who have just started getting their periods. This causes a hormone imbalance where the estrogen in your body makes the lining of your uterus (called the endometrium) grow until it gets too thick. When your body gets rid of this linin