Whether 6 mm of endometrial lining is normal or not depends on which time of the menstrual cycle the test is done. If the ultrasound is done before menstruation, the thickness of the endometrium is only 6 mm, suggesting that the endometrium is too thin, this situation may cause low menstrual flow, and it has a certain effect on pregnancy, and the endometrium is thin, which is not conducive to the fertilization of the egg to settle down; if the ultrasound is done after the menstrual cycle has been cleaned up for 3-4 days, and the endometrium is 6 mm, it is a normal phenomenon. The lining of the uterus varies in thickness at different times of the menstrual cycle and proliferates and sloughs off with changes in hormone levels in the body. If the lining of the uterus is relatively thin, you can usually take appropriate medication to regulate, for example, you can choose Chinese medicine to regulate menstruation and promote pregnancy pills, you can also choose short-acting contraceptive pills to regulate, under the guidance of the doctor to use medication.