A significant percentage of infertile women who visit our center have a thin endometrium. Today, let’s learn about the common causes of a thin endometrium and how to manage it. Definition of thin endometrium Thin endometrium is defined as the thickness of the endometrium that is below the threshold thickness for being able to obtain a pregnancy. Currently, there is no uniformity regarding the criteria for this threshold, and most scholars consider thin endometrium as having an endometrial thickness <7 mm measured by transvaginal ultrasound on the day of HCG in ART. Main causes of thin endometrium 1, inflammation Various acute and chronic gynecological inflammatory diseases such as endometrial tuberculosis, inflammation or secondary infection caused by spontaneous abortion, and other inflammatory diseases involving the uterine cavity may cause endometrial cell damage and death, resulting in thin endometrium, atrophy of glands and interstitium, as well as proliferation of fibrous tissue in the uterine cavity and subsequent scarring. 2. Drug-related injury Oral contraceptives: For older patients or those with poor ovarian function, in order to obtain relatively more and better quality eggs in a shorter period of time from the patient's point of view, ovulation is usually promoted with microstimulation protocols, such as clomiphene (CC). However, while promoting ovulation, CC can directly affect the endometrial development due to its anti-estrogenic effect, thus affecting the endometrial tolerance and reducing the pregnancy rate. 3, medically induced injury During various uterine operations such as uterine clearance, endometrial ablation and myomectomy, if the endometrial tissue is too fragile or the surgical operation is too hard, it can lead to endometrial basal layer injury. 4. unexplained thin endometrium Treatment of thin endometrium 1. high-dose estrogen replacement therapy The routes of estrogen administration are oral, transdermal, transvaginal, etc. For patients with freeze-thaw embryo transfer, the most used should be oral Glivec, the specific oral dose is shown in the common drugs section of this public website; or subcutaneous injection of HCG on top of estrogen can also increase the endometrial thickness; other routes of medication include Comerva skin patch, Estrogen gel, vaginal fenomorphine, etc.; gonadotropin-releasing hormone agonist (GnRHa). 2.Treatment to improve blood perfusion Low-dose aspirin (refer to previous push content); vitamin E with hexoketococine (PTX); L-arginine; sildenafil citrate; pelvic floor neuromuscular electrical stimulation (NEMS); hyperbaric oxygen therapy. 3.Treatment to promote endothelial cell proliferation or regeneration Uterine physical manipulation (endothelial scratching); granulocyte colony-stimulating factor (G-CSF); growth hormone (GH); stem cell therapy; platelet-rich plasma autotransplantation. 4.Chinese herbal medicine Long Lu capsule, Jia Wei biochemical granules, Hong Hua Yi Yao tablets and other blood-activating and stasis-transforming Chinese medicines can also assist in improving endometrial blood flow to a certain extent, and then improve the condition of endometrium.