Blood clots during a period are caused by the body's natural process to control bleeding as the uterine lining sheds. When menstrual blood flow is heavy, blood can pool in the uterus and coagulate, forming clots. Normally, the body produces anticoagulants to help thin the blood and allow it to flow freely, but if bleeding is heavy, the amount of blood can outpace the body's ability to thin it, leading to clot formation
. Several factors and conditions can cause or contribute to blood clots during menstruation:
- Hormonal imbalances: Fluctuations in estrogen and progesterone affect the thickness of the uterine lining and menstrual flow, potentially causing heavy bleeding and clots. Conditions like perimenopause, menopause, stress, or significant weight changes can disrupt hormone levels
- Uterine abnormalities:
- Fibroids: Noncancerous muscular tumors that grow in the uterine wall can cause heavier menstrual bleeding and clots
* **Polyps:** Benign growths on the cervix or uterine lining can increase bleeding and clotting
* **Adenomyosis:** When the uterine lining grows into the muscular wall, thickening the uterus and causing heavy bleeding and clots
* **Endometriosis:** Uterine lining tissue growing outside the uterus leads to heavy, painful periods with clots
* **Enlarged uterus:** Post-pregnancy or structural changes can allow more blood to pool, increasing clot risk
- Pregnancy loss or miscarriage: Early pregnancy loss can cause heavy bleeding and passing of large clots, sometimes mistaken for a heavy period
- Blood disorders: Conditions like von Willebrand disease can impair clotting, paradoxically causing heavy bleeding and clots
- Medications and birth control: Some hormonal contraceptives and medications, including anticoagulants and anti-inflammatory drugs, can affect menstrual bleeding and clotting
In summary, blood clots during periods result from heavy menstrual bleeding where blood pools and coagulates inside the uterus. Underlying causes include hormonal imbalances, uterine growths (fibroids, polyps), conditions like endometriosis and adenomyosis, pregnancy loss, blood disorders, and certain medications
. If clots are large, frequent, or accompanied by other symptoms such as severe pain or fatigue, medical evaluation is recommended.
