Children's Hospital Colorado

Heavy or Abnormal Menstrual Bleeding

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What is heavy or abnormal menstrual bleeding?

We consider a menstrual period to be heavy or abnormal if it lasts longer than eight days in a row. Heavy or abnormal menstrual periods also include bleeding that occurs more often than every three weeks and requires changing a pad or tampon every hour or less during menstruation. Heavy menstrual bleeding may also cause fatigue, dizziness or other signs of anemia. Anemia is caused by a lower-than-average amount of healthy red blood cells.

What causes heavy or abnormal menstrual bleeding?

Heavy or abnormal menstrual bleeding most often occurs because of an imbalance of hormones. The body produces a female hormone called estrogen at the beginning of puberty. Estrogen causes the lining of the uterus to grow thicker. The body also makes a hormone called progesterone after ovulation. Progesterone causes the lining of the uterus to mature and thin over time.

For many, ovulation does not occur regularly in the first several years after getting the first period. Without monthly ovulation, the lining of the uterus grows thicker due to the presence of estrogen without the balance of progesterone. This causes irregular, frequent, heavy and prolonged periods.

Another much less common cause of heavy bleeding is a bleeding disorder, which means the blood is not clotting as it should. Structural problems like fibroids, polyps or other growths are rarely the cause of heavy bleeding.

Who gets heavy or abnormal menstrual bleeding?

Heavy menstrual bleeding due to hormonal factors is more common in the first few years after getting a menstrual period. This is because it often takes several years to have regular and monthly ovulatory cycles.

Heavy menstrual bleeding due to a bleeding disorder is often due to an inherited or genetic condition. Let your doctor know if there is a family history of heavy bleeding in any close relative like siblings, parents or grandparents.

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Get to know our pediatric experts.

Stephen Scott, MD

Stephen Scott, MD

Ob/Gyn Obstetrics & Gynecology

Veronica Alaniz, MD

Veronica Alaniz, MD

Ob/Gyn Obstetrics & Gynecology