Failure of embryo implantation may be caused by insufficient luteal function, uterine factors, and uncoordinated development of endometrium and embryo. 1. Luteal insufficiency: Insufficient luteal function in the body, abnormal secretion of estrogen and progesterone, poor endometrial tolerance, and inability to prepare the endometrium for the embryo’s implantation. 2. Uterine factors: the presence of endometrial polyps, uterine submucosal fibroids, uterine adhesions and other abnormal anatomical conditions can lead to an abnormal environment for embryo implantation, resulting in implantation failure. 3. Endometrium and embryo development is not coordinated: endometrium and embryo development synchronization is a necessary condition for the fertilized egg implantation, if the endometrium development and embryo development is not coordinated will also lead to not implantation. There are many reasons why the embryo does not implant, and if a woman has multiple spontaneous abortions or biochemical pregnancies, she needs to consult a doctor in a timely manner for examination, clarification of the causes, and targeted treatment.