Most of the cases of menstruation but no decrease in basal body temperature are caused by luteal atrophy. For various reasons, the regulation of hypothalamic-pituitary-ovarian axis is disturbed, or the luteolysis mechanism is abnormal, resulting in the luteolysis not shrinking in time, the endometrium will still be affected by progesterone, so that the endometrium can not be completely shed, the patient will have a prolonged menstrual period, the temperature can not be completely lowered phenomenon, such patients should do diagnostic scraping on the 5th-6th day of menstruation, pathology The endometrium can still be seen in a secretory reaction on examination. Therefore, if a woman has prolonged periods for a long time, she needs to be treated with oral progestin medication under the guidance of a doctor.