The endometrial lining of 14mm without menstruation is considered to be related to pregnancy, mental stress or polycystic ovary syndrome, premature ovarian failure and other gynecological endocrine diseases. 1. pregnancy: women of childbearing age who have had unprotected sex and do not menstruate with an endometrium of 14mm should first be excluded from the possibility of pregnancy, and it is recommended to take a pregnancy test or blood HCG test. 2. Mental stress: if the patient recently work and study pressure or often stay up late, it is easy to lead to endocrine disorders, thus affecting the normal ovulation function, resulting in the endometrium can not be completely stripped and the endometrium thickening and menstruation will not be tide of the performance. 3. Gynecological endocrine diseases: (1) Polycystic Ovary Syndrome (PCOS): due to the high level of androgens in the body, which inhibits the function of the female gonadal axis, the follicles cannot grow and develop normally and are discharged, resulting in the endometrium not being able to be completely stripped off and the menstrual period cannot come. (2) Premature Ovarian Failure: Due to the decrease of ovarian function, the level of estrogen in the body decreases significantly, the follicles in the ovary cannot develop and grow up to be discharged, and the level of progesterone produced is also on the low side, which affects the stripping of the endometrium and results in the thickening of the uterine endometrium. For women who do not have menstruation even if their uterine lining is 14mm, it is recommended that they complete sex hormone and other relevant examinations to clarify the cause of the disease and then actively treat the disease under the guidance of the doctor.