If the thickness of the endometrium is only 6mm during ovulation, it is very difficult to get pregnant. With such a thin endometrium, there is no place for the fertilized egg to settle after it enters the uterine cavity, and it flows out directly and cannot get pregnant. The most common causes are as follows: 1. endocrine disorders, insufficient hormone levels in the body or thinning of the endometrium due to ovarian decline; 2. a history of uterine cavity manipulation, resulting in incomplete adhesion of the uterine cavity, which can lead to a thin endometrium. Once diagnosed, the adhesions can be separated through hysteroscopy and treated with postoperative medication to restore the endometrium to its normal thickness.