Endometrial thickness of 14mm bleeding is the result of endometrial thickening, endometrial polyps, endometrial cancer and other diseases. 1. Endometrial thickening: the main cause of endometrial thickening is long-term estrogen stimulation without progesterone antagonism. Patients may have abnormal endometrial thickening, which can reach 14mm, accompanied by abnormal uterine bleeding, manifested as long bleeding time, increased bleeding volume, non-menstrual vaginal bleeding, etc. 2. Endometrial polyp: The formation of endometrial polyp is related to the high estrogen level, when the estrogen level rises continuously, it will lead to the thickening of endometrial lining, which can be up to 14mm, and endometrial polyp can be formed by the long-term high level of stimulation. Patients may have abnormal uterine bleeding, excessive menstrual flow, prolonged menstrual period and other symptoms. 3. Endometrial cancer: when estrogen overstimulates the endometrium, it will lead to reproductive endocrine disorder and induce endometrial cancer. If the thickness of endometrial lining of postmenopausal women reaches 14mm, accompanied by abnormal vaginal bleeding, lower abdominal discomfort and other symptoms, endometrial cancer is most likely to be considered. There are many reasons leading to endometrial thickness of 14mm bleeding, patients are advised to go to regular hospitals to find out the causes of the disease.