The endometrium here refers to the uterine lining, endometrium thickness of 9mm does not come to menstruation may be the menstrual period, pregnancy, endocrine disorders and other reasons. 1. Menstruation: most women will have menstruation when the thickness of the endometrium reaches 10~12mm, but there is a difference between individuals, the endometrium thickness of 9mm does not come to menstruation, it may be that the menstruation period has not yet arrived, you can continue to observe the menstruation is delayed or advance a week of time is normal. 2. pregnancy: usually have sex with women, do not do a good job of contraception or contraceptive failure, may also be endometrial thickness of 9mm does not come to menstruation, considering the cause of pregnancy, early pregnancy endometrial thickness of about 8 ~ 12mm or so, after the fertilized egg implantation of the endometrium will be further proliferation, by the luteinizing body of pregnancy after the formation of the ecchymosis, the success of the woman’s menstruation will be suspended after the pregnancy does not come. 3. Endocrine disorders: the usual mental stress, long hours of late night, excessive weight loss, polycystic ovary syndrome and other factors will cause the body’s endocrine disorders, will also have endometrial thickness of 9mm, but the performance of menstruation does not come. If you have a 9mm thick uterine lining and never get your period, you should go to the hospital to check the cause and treat the symptoms.