It is impossible to make a generalization about the number of days after blastocyst transfer, but a case-by-case analysis is needed. If the transferred blastocysts successfully implant, most of the time, around 7-8 days after the transfer, the chorionic gonadotropin level will be elevated and can be considered as successful pregnancy when it exceeds 25 IU/L. If the blastocyst is slow to develop after transfer to the uterine cavity or if the implantation is late, it is normal to find elevated chorionic gonadotropin levels only 10-15 days after transfer. Ultrasound can usually be done after 20-35 days of transfer to determine if the embryos are in the uterine cavity. After blastocyst transfer, you should pay attention to proper rest, maintain a regular lifestyle, and increase nutrition by eating foods rich in protein, vitamins and folic acid to provide the body with sufficient nutritional supply to facilitate the growth and development of the blastocyst.