Blastocysts of 5bc are of medium to high grade. Blastocyst grades are categorized into four grades; grade a is a good quality blastocyst, grade b is a better quality blastocyst, grade c is a poorer blastocyst, and grade d blastocysts need to be eliminated. Blastocysts are generally represented by a number and two letters, and blastocyst 5bc is an intermediate to high grade. The 5 in 5bc indicates that the blastocyst is at stage 5 of development and is more mature. The second b indicates the grading of the cell mass inside the blastocyst and the third c indicates the grading of the cells in the trophoblast layer of the blastocyst. bc in combination indicates that the cells of the blastocyst are more sparsely arranged and are not very numerous. The 5bc blastocysts have met the criteria for embryo transfer, as they are of medium to high grade, and they have a high likelihood of transfer failure. Blastocyst culture requires high conditions, not all cleavage stage embryos can be cultured into blastocysts, and good quality embryos have a relatively higher chance of developing into blastocysts. Therefore, the process of blastocyst culture is also a process of elimination of the best and the worst, which can screen out embryos with higher developmental and implantation potentials, and the probability of successful pregnancy after transferring to the mother is relatively high.