How does the menstrual cycle shorten and the menstrual volume increase?

Shortened menstrual cycles and increased menstrual flow may be caused by changes in hormone levels in the body. However, there are also cases of uterine fibroids, endometriosis, endometrial polyps, intrauterine device stimulation, primary hypothyroidism, blood system diseases, autoimmune diseases, etc., which can also cause shortened menstrual cycles and increased menstrual flow. Under normal circumstances, women's menstrual cycle is generally about 28 days, early or pushed back within a week are normal, menstrual blood volume is generally 30-50ml, more than 80ml for menstrual volume increase.