The 5-day blastocysts will implant in the uterine cavity at the latest at around 7 days, but there will be individual differences. The fertilized egg enters the uterine cavity and implants into the uterine lining after developing into a 5-day blastocyst, and this process, i.e., implantation, needs to go through three processes, namely, localization, adhesion and invasion, and in general, the 5-day blastocyst will complete implantation at the latest when it reaches about 7 days. However, since the blastocyst implantation is also affected by the level of progesterone and the tolerance of the endometrium, the time of implantation will also have individual differences. HCG (human chorionic gonadotropin) levels are secreted about 1 day after the 5-day blastocyst implantation, and pregnancy can be determined by blood HCG levels about 10 days after intercourse. Under the guidance of your doctor, an ultrasound will be performed at around 40 days after menopause to confirm intrauterine pregnancy, and you should follow your doctor’s instructions to have regular checkups.