A week early menstruation is basically normal, but low menstrual volume and dark color are abnormal, indicating that the menstrual blood is not discharged smoothly. If a woman eats too cold food within one week before her menstrual period, the cold stimulation will lead to vasoconstriction, which will cause the endometrium to peel off and significantly reduce the bleeding volume, plus the abnormal contraction of the uterus, which will cause the blood to stay in the uterine cavity for too long and lead to low menstrual volume and black color. The endometrial lining is severely damaged, and the endometrial lining is poorly proliferated by estrogen, which can also cause a significant decrease in menstrual volume and abnormal color due to prolonged stay in the uterine cavity, and chronic inflammatory diseases of the endometrium can also affect menstrual volume and the color of menstrual blood.