Why is menstruation half a month earlier

Menstruation ahead of half a month belongs to abnormal uterine bleeding, the possible reasons are as follows: first, endocrine factors and improper use of sex hormones, or intrauterine device foreign body stimulation. Second, endometrial polyps, endometrial fibroids, cervical cancer, endometrial cancer. Third, inflammation including pelvic inflammatory disease, cervicitis, endometriosis. Fourth, to rule out pregnancy-related diseases, including abortion, ectopic pregnancy and trophoblastic disease, do a urine pregnancy test can rule out. Fifth, internal diseases of the blood system and diseases such as hyperthyroidism can also cause abnormal uterine bleeding.