The endometrium is 12mm, a condition that indicates that menstruation is imminent and that you may also be pregnant. The thickness of the endometrium varies at different times of the menstrual cycle, usually before menstruation, the endometrium is thicker, and the thickness may reach 10~12mm. Now the ultrasound examination of the uterine lining of 12mm, it is possible that the menstruation is coming soon, you can observe and see. Some women may experience some uncomfortable symptoms before menstruation due to fluctuations in hormone levels, such as emotional irritability, breast swelling, headache, dizziness, insomnia and other symptoms. Women who are sexually active should also check if they are pregnant if they have an ultrasound that reveals a 12mm uterine lining after their period has been delayed, which can be tested with an early pregnancy test. Because after pregnancy, the uterine lining will also gradually thicken, which is conducive to the growth and development of the embryo.