The process of embryo implantation refers to the process of fertilized egg implantation, including localization, adhesion and invasion processes. 1. Localization: is the process by which the zona pellucida disappears and the late blastocyst localizes in the endometrium. Late blastocysts localize mainly by contacting the endometrium with the endocellular mass of the blastocyst. 2. Adhesion: It is the process of adhesion of late blastocysts to the endometrium and the differentiation of trophoblast cells on its surface. It mainly differentiates into the outer layer of syncytiotrophoblasts and the inner layer of cytotrophoblasts. 3. Invasion: It is the process in which the trophoblast cells penetrate and invade the endometrium, the inner 1/3 of the myometrium and the blood vessels, and the blastocyst is completely buried in and covered by the endometrium. Fertilized egg implantation often occurs on day 6-7 after fertilization, and there is a very short sensitive period in the uterus to allow the implantation of the fertilized egg. If there is any discomfort, it is advisable to seek medical attention and treatment.