Heavy Menstrual Bleeding Explained

Heavy menstrual bleeding (HMB) is not normal. HMB refers to an excess of blood loss during your menstrual period. The question is how much is too much? In a “normal” menstrual cycle, a woman loses 2 to 3 tablespoons (35 to 40 milliliters) of blood over four to eight days on average. 1 However, this data is from an outdated study from Norway that only included Caucasian women. Some women lose a lot more blood. This is referred to as heavy or prolonged menstrual bleeding or menorrhagia.2 Most women have a menstrual period every 24 to 38 days. That is, the time from the first day of one menstrual period to the onset of the next. The average is every 28 days. Women who lose more than 5 to 6 tablespoons (about 80 milliliters) of blood during their menstrual period are defined as having HMB for clinical research purposes. In regular medical practice, exact measurements of blood loss are not easily obtained. With HMB, losing a lot of blood during a period can cause medical problems such as anemia.


Below are signs of experiencing heavy blood loss with your periods3 :

  • Soaking through one or more sanitary pads or tampons every hour for several hours
  • Using double sanitary protection to control your menstrual flow
  • Waking up to change sanitary protection during the night
  • Bleeding for longer than a week
  • Passing blood clots larger than a quarter
  • Restricting daily activities due to heavy menstrual flow
  • Symptoms of anemia such as tiredness, fatigue, or shortness of breath.

What is Anemia and How is it Related to HMB?

Anemia is a condition caused by a low quantity of red blood cells. This results in the inability to transport oxygen to your body’s tissues.4 In a routine blood test, anemia is defined as low hemoglobin or hematocrit. Hemoglobin is the main protein in your red blood cells (RBCs). It is the iron containing molecule that carries oxygen and delivers it throughout your body.5 Iron is a critical component of hemoglobin. Without iron, hemoglobin cannot be formed and fewer red blood cells are produced. Hematocrit (Hct) is the percent of a sample of blood made up of RBCs.

If you have anemia, your hemoglobin level will be low too. If it is too low, your tissues or organs may not get enough oxygen. When your hemoglobin levels are low, your body tries to compensate by using iron to make more hemoglobin. This can lead to an iron deficiency, resulting in anemia.

There are many causes of anemia, one of them could be heavy menstrual bleeding.

Symptoms of HMB related anemia6 include:

  • Weakness
  • Headache
  • Irritability
  • Fatigue
  • Difficulty exercising (due to shortness of breath, rapid heartbeat)
  • Brittle nails
  • Sore tongue
  • Restless legs syndrome
  • Pica (an abnormal craving to eat non-food items, such as clay or dirt, paper products, or
  • Pagophagia (an abnormal craving to eat ice)

If you have any of these symptoms, please contact your health care provider as soon as possible.


How is HMB Related Anemia Diagnosed?

A complete blood count (CBC) test will measure your red blood cells, hemoglobin, and other
components of your blood.7 Your doctor will ask about your family history and your medical history.
After the CBC, they may do other tests to determine the cause of anemia.

How is HMB Related Anemia Treated?


The main objective would be to treat the Heavy Menstrual Bleeding. Treatment will be based on the specific cause of the HMB. There are medical, surgical and procedural treatment options for HMB.8 Talk with your doctor about which treatment option may be right for you.


Anemia due to blood loss and iron-deficiency can usually be treated with iron and dietary adjustments. Depending on the severity, you may need a blood transfusion or an iron infusion to increase your hemoglobin level and ensure enough oxygen is being delivered to your organs and tissues.9

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