Passing blood clots during a period can be normal and usually happens due to abnormal hormone levels that cause the lining of the uterine walls to thicken. This can result in heavier bleeding and the formation of clots ranging from 5 mm to 3-4 cm (about an inch).

However, although having a period with blood clots is normal in most cases and does not require treatment, in other cases it can be a sign of by diseases such as anemia, endometriosis or fibroids, especially if clots are passed with fleshy tissue.

It is important to see your doctor to assess what is causing blood clots during your period and to indicate the best treatment. The doctor may order bloodwork to assess your body‘s clotting abilities, as well as an ultrasound to assess your uterine lining.

What causes period blood clots?

The most common causes of a blood clots during a period include:

1. Miscarriage

Blood clots during a period may indicate miscarriage in the first trimester of pregnancy, especially if the clot color is slightly yellowish or grayish. It is also common to pass fleshy tissue. Learn more about miscarriage symptoms that can occur in addition to blood blots.

What to do: To confirm if you are experiencing a miscarriage, it is very important to seek urgent medical attention doctor. If the bleeding is very heavy, you should proceed to the hospital immediately to start appropriate treatment and to prevent excessive blood loss. In most cases, miscarriages occur in the first weeks of pregnancy and bleeding lasts for about 2 to 3 days.

2. Endometriosis

Endometriosis is characterized by the growth of endometrial tissue outside the uterus, which can lead to heavy menstruation, intense pain and clot formation. Although this disorder is more frequent in women between the ages of 30 and 40, it can appear at any age.

Read more about the endometriosis symptoms that can present and how they vary from woman to woman.

What to do: You should see your doctor for testing (e.g. a transvaginal ultrasound or blood test) to confirm a diagnosis,. Starting treatment usually depends on the woman's desire to get pregnant and can be done with the use of medication, hormones or surgery.

3. Uterine fibroid

A uterine fibroid, or myoma is a benign tumor that grows on the inner wall of the uterus. It usually causes symptoms such as pain in the uterus, heavy menstruation with the formation of clots or fleshy tissue, and bleeding between periods.

What to do: It is important to see your doctor, who can order a pelvic ultrasound and confirm the presence of the myoma. Treatment can be done with medication, surgical removal of the fibroid or fibroid embolization.

4. Iron deficiency anemia

Iron deficiency anemia may be one of the causes of a period with clots, since iron deficiency can alter blood clotting and lead to menstrual clots. See the main symptoms of anemia to determine your risk for this condition.

What to do: It is important to see your doctor to request a blood test to confirm anemia. If confirmed, anemia can be treated with an iron supplement, prescribed by the doctor, and by increasing intake of iron-rich foods such as lentils, parsley, beans, and meat.

Read more about the anemia diet and how to get started.

5. Other diseases that affect the endometrium

Other endometrial diseases such as endometrial hyperplasia, which is the overgrowth of the endometrium, or endometrial polyps, which is the formation of polyps in the endometrium, can lead to a period with clots due to abnormal growths of the uterus.

What to do: You should see your gynecologist to diagnose the underlying cause promptly. Treatment can be done with the curettage of the endometrial tissue or with the use of progesterone.

6. Vitamin and mineral deficiency

A deficiency in vitamins and minerals that regulate the formation of clots (e.g. vitamin C or K deficiency) can alter the body's ability to clot, and which can result in clots during your period.

What to do: In these cases, it is important to increase your intake of foods like spinach, oranges, strawberries, broccoli or carrots, for example.

7. Gynecological examinations or childbirth

Periods with clots may also occur after gynecological examinations or because of complications during childbirth.

What to do: Following a gynecological procedure, a period can vary for 2 or 3 days, and then resolve and return completely to normal by the next cycle. However, if clots continue to appear, it is important to see your gynecologist for follow-up.

Fleshy tissue with a period

Your period can also come with small pieces of fleshy tissue and this does not mean that the woman has had a miscarriage. These pieces of tissue are little bits of the woman's own endometrium, but they are colorless. Just as the blood has red cells and white cells, the endometrium can also have this coloration.

If your menstruation has pieces of fleshy tissue for 2 consecutive cycles, see your gynecologist for assessment and ask if testing if necessary.