The fertilized egg is also known as the fertilized ovum. Generally, the fertilized ovum is implanted in the endometrium after 6 to 7 days of fertilization, that is, it is implanted, and it is implanted on the 24th day of menstruation at the latest. The fertilized egg needs to go through three processes: localization, adhesion and invasion. Successful implantation requires the endometrium, which is supported by the estrogen and progesterone secreted by the corpus luteum, to be tolerant, and the endometrium is tolerant only between the 20th and 24th day of the menstrual cycle, so the fertilized egg has to be implanted on the 24th day of the menstrual cycle at the latest. The conditions necessary for fertilization are the disappearance of the zona pellucida, the differentiation of blastocyst trophoblast cells into syncytial trophoblast cells, the synchronized and coordinated development of the blastocyst and the endometrium, and the secretion of adequate amounts of estrogen and progesterone. Failure of one of these conditions during the endometrial receptive phase can also affect the implantation of a fertilized egg. It is clinically recommended to keep a good state of mind when preparing for pregnancy, so as to promote the stabilization of hormone levels in the body, which is conducive to the normal development of the embryo, and to pay attention to regular check-ups in the hospital to ensure that the fertilized egg is properly implanted.