Blastocyst rearing is the continuation of in vitro culture of day 3 embryos to become day 5-6 blastocysts. The egg and sperm form a fertilized egg and continue to divide, forming an embryo consisting of 5-10 cells on day 3, which is often referred to as a day 3 embryo. In vitro culture continues and the cells continue to divide, forming a mass of 100 cells or more on day 5-6, the blastocyst. The advantage of blastocyst is that the embryo has good developmental potential and is more compatible with human physiology, so the transfer rate is higher. The success rate of blastocyst transfer is 20% higher than the pregnancy rate of day 3 embryos, while at the same time reducing the incidence of ectopic pregnancy and also reducing the rate of multiple births. Blastocyst transfer is recommended preferably for patients with unexplained repeated implantation failures, history of multiple miscarriages, and multiple ectopic pregnancies. However, there are risks associated with blastocyst transfer, as more than half of the embryos may stop developing during the blastocyst culture process, resulting in no embryo transfer.