Heavy or prolonged menstrual bleeding is known as menorrhagia. The causes of menorrhagia can be divided into three categories:

1. Uterine-related problems: These include fibroids, polyps, adenomyosis, and cancer of the uterus or cervix.

2. Hormone problems: Hormone imbalances, such as an imbalance of estrogen and progesterone, can cause heavy bleeding. Other hormone-related causes include endometrial hyperplasia and the use of hormone contraception such as the Pill or a progestogen IUD.

3. Other health conditions: Certain medical conditions, such as thyroid, kidney, or liver disease, and bleeding disorders like von Willebrands disease, can cause heavy menstrual bleeding. Additionally, some medications, such as blood thinners and hormonal medicines like birth control pills, can result in heavy or lengthy menstrual bleeding.

In some cases, the cause of menorrhagia is unknown. Menorrhagia can lead to anemia, which can cause fatigue, weakness, and shortness of breath. If you experience heavy or prolonged menstrual bleeding, you should see your doctor for a diagnosis and treatment options.