The endometrium is divided into a basal layer and a functional layer. The basal layer is not affected by estrogen and progesterone, while the thickness of the functional layer changes with the changes of estrogen and progesterone during the menstrual cycle. Before ovulation, the endometrium is proliferative and grows under the action of estrogen, and after ovulation it is transformed into secretory endometrium by the action of progesterone. If no conception occurs, during menstruation, the functional layer of the endometrium will shed and bleed, followed by regeneration of a new functional layer from the basal layer. The thickness of the endometrium during ovulation <7mm is generally considered as thin endometrium. Pregnancy is like a farmer planting a crop, it needs good seeds (embryos) and fertile land (endometrium) to get a good harvest (pregnancy outcome), thin endometrium definitely has some effect on pregnancy, and the treatment varies depending on the cause. The first thing to consider in cases of thin endometrium secondary to abortion is the adhesion of the uterine cavity caused by the clearance procedure, which can be diagnosed by hysteroscopy and the adhesions can be separated by hysteroscopy. Injury to the basal lamina Clearance surgery may result in injury to the basal lamina of the endometrium, which prevents the growth of a new functional lamina; in the case of injury to the basal lamina, there is no better treatment available. Endometritis Surgical operations in the uterus and upstream infections in the reproductive tract may lead to endometritis and subsequently to uterine adhesions. Endocrine factors The endometrium of the functional layer grows by the action of estrogen. If there is no ovulation, poor follicle quality or use of clomiphene to promote ovulation, etc., low estrogen levels may also lead to thin endometrium. You can monitor ovulation and endometrial condition by ultrasound, supplement exogenous estrogen appropriately and promote ovulation treatment under the guidance of a doctor. Other factors Many factors such as certain endocrine diseases and emotions can also affect follicle growth and lead to thin endometrium. In conclusion, it is recommended to improve the examination and cooperate with the doctor to actively look for the causes of endometrial thinning and to carry out targeted treatment, as well as to adjust the mentality.