Why do blood clots occur during menstruation?

Menstrual clots are normal in many women, especially in the first days of menstruation when there is more bleeding. However, if the clots are of considerable size, frequent or if they are accompanied by symptoms such as heavy bleeding or menstrual pain, a specialist should be consulted.
Egg and sperm donation magazine

Menstrual Clots: Causes, Diagnosis, Treatment & More

Period Blood Clots: When They Are Normal and When to Be Concerned

Menorrhagia: Signs You're Losing Too Much Blood During Your Period

Passing Blood Clots When Not on Your Period

Is It Normal for Period Blood to Come Out in Clumps? (for Teens)

Why Is My Period Blood Brown? Period Blood Color, Explained

Endometriosis period blood: Color, clots, appearance, and more

Are Blood Clots During Menstruation Normal? Expert Explains Potential Causes

Blood Clots During Your Period - What You Should Know