Causes of Constant Menstrual Bleeding

A woman of childbearing age typically has a monthly period with menstrual flow lasting from 2 to 7 days. In some women, menstrual bleeding may be irregular, occurring either intermittently or continuously throughout the month. This abnormal bleeding pattern has several possible causes and is often due to hormonal problems. Although most underlying problems are not serious, a few may be cause for concern. If you experience prolonged bleeding or menstrual irregularity, talk with your doctor.

Causes of Constant Menstrual Bleeding Credit: Piotr Marcinski/iStock/Getty Images

Ovulation Problems

During a normal menstrual cycle, the ovaries produce female hormones that cause ovulation at the midpoint of the cycle. These hormones also simulate growth of the uterine lining to prepare for an embryo. When a woman experiences constant menstrual bleeding, which can be heavy, it's called dysfunctional uterine bleeding (DUB). DUB is often caused by failure of the ovary to release an egg, called anovulation. If ovulation does not occur, the female hormone progesterone may be low, while estrogen could remain too high. This hormonal imbalance can lead to intermittent or constant spotting throughout the cycle, called breakthrough bleeding.

Noncancerous Uterine Growths

Heavy or constant menstrual flow might be caused by noncancerous tumors in the uterus called fibroids. These tumors form in the uterine wall and can cause spotting throughout the cycle and heavy, painful periods. Another type of benign growth, called a polyp, can develop in the uterine lining and cause constant or intermittent bleeding. Treatment with hormones often helps alleviate bleeding, but the best course of treatment depends on the age of the woman and her plans for having children in future.


Some women who use an intrauterine device (IUD) for contraception experience spotting or intermittent bleeding throughout the menstrual cycle. This is more likely in users of copper-containing IUDs, according to an article published in the May 2013 issue of "Contraception." Nonsteroidal antiinflammatory drugs, such as ibuprofen (Motrin, Advil) and naproxen (Aleve, Naprosyn), reduce bleeding associated with an IUD, according to an October 2009 review published in the "Cochrane Database of Systematic Reviews." Some women may need to consider IUD removal if bleeding continues or is heavy.

Endometrial Cancer

In rare cases, uterine cancer -- also known as endometrial cancer -- can cause constant or irregular menstrual bleeding. This form of cancer is most common in women over age 55 who have entered menopause, but it can develop at any age. Other symptoms may include pelvic pain or pain while urinating or during sexual intercourse. Any postmenopausal women experiencing vaginal bleeding should see her doctor as soon as possible.


Occasionally, an infection in the vagina or fallopian tubes might cause spotting or constant bleeding during the menstrual cycle, especially if the problem goes undetected and becomes severe. Infection of the uterus and fallopian tubes, known as pelvic inflammatory disease or PID, requires urgent antibiotic treatment to avoid possible damage to the reproductive organs and infertility. One in 8 women who have had PID experience fertility problems, according to the Centers for Disease Control and Prevention.

Other Causes

A problem unrelated to the reproductive system sometimes causes persistent vaginal bleeding. For example, a woman with a bleeding disorder might bleed throughout the month. Certain autoimmune diseases, such as systemic lupus erythematosus and a type of hypothyroidism called Hashimoto disease, can also cause irregular or constant bleeding, along with other symptoms. Some women with type 1 diabetes also have menstrual problems that can include prolonged bleeding, especially between the ages of 20 and 30, according to a study published in the April 2003 issue of "Diabetes Care."

Reviewed by: Tina M. St. John, M.D.

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