What does blastocyst transfer mean? In our center, conventional embryo transfer is performed 3 days after egg retrieval, when the embryo contains 5-8 cells. Blastocyst transfer means that the embryo is cultured in vitro for 5-6 days, containing about hundreds of cells, to form a blastocyst and then implanted into the uterine cavity. The fact that a fertilized egg can develop into a blastocyst in vitro proves to some extent that it is viable and the success rate of the transfer is high. What are the advantages and disadvantages of blastocyst transfer? The main advantage of transferring embryos at the blastocyst stage is the higher rate of implantation of blastocysts. Not only can doctors transfer fewer blastocysts, but they can achieve a higher pregnancy rate, thus minimizing the risk of multiple births. The disadvantage is that only 40-50% of the embryos will develop to the blastocyst stage and if the patient has a low number of embryos or poor quality embryos, there is a risk that they will not develop to the blastocyst stage and no embryos will be transferred. Embryos that do not survive in the laboratory may survive in utero if transferred early. It is like a natural selection process, and those that remain are the promising seeds!