The blastocyst usually does not come to bed on the 5th day after fertilization. The sperm unites with the egg to form a fertilized egg, and it takes some time for the fertilized egg to come to bed, and this time varies from person to person, usually 6-7 days, and the woman usually does not feel anything special during the process of coming to bed. The sperm enters the fallopian tube about 30 hours later and unites with the egg to form a fertilized egg. 3 days later, the fertilized egg undergoes egg cleavage while running in the reverse direction to the uterine cavity, and the fertilized egg is called a blastocyst at this stage. At this stage, the endometrium secretes some nutrients to fully prepare the blastocyst for implantation. The fertilized egg needs enough progesterone, a sex hormone secreted by the oocyte, which can reduce the excitability and sensitivity of the smooth muscle of the uterus and can promote the successful implantation of the blastocyst. Poor quality embryos that do not have the potential for implantation and development; abnormal endometrium, such as cavity adhesions and abnormal endometrial hyperplasia; too thick endometrium and inadequate endometrial blood supply are not conducive to implantation, so you should go to a regular institution for relevant examinations before preparing for pregnancy. When preparing for pregnancy, you should maintain good living habits, prohibit smoking, limit the intake of alcohol and coffee, eat more foods with high vitamin content, and take appropriate amounts of protein, folic acid and various trace elements required by the human body to ensure adequate intake of nutrients.