1. Why do some eggs not fertilize? Egg fertilization is a complex process, and scientific research does not yet fully understand the mechanisms involved in the entire fertilization process. What is known about the process of fertilization includes the maturation of the egg, the acquisition of sperm, the acrosome reaction and crossing of the egg zona pellucida, the fusion of the sperm with the egg membrane, the cortical reaction of the egg, the resumption of meiosis and the formation of the male and female protoplast. A problem in any of these processes can lead to failure of fertilization. In IVF technology, possible causes of egg non-fertilization include immature eggs, eggs that are mature but of questionable quality, and abnormal sperm morphology and function, thus affecting one or more of the above mentioned fertilization processes. 2. Why don’t we do blastocyst culture? Because the environment of the uterus is more conducive to embryo growth than that of the incubator. However, so far, there is no good blastocyst culture technology internationally, and no matter how to do it, the blastocyst formation rate is only 30~50%. The implantation rate of our third day embryos is 32%, and if the implantation rate of blastocysts reaches 64% to balance, but the implantation rate of blastocysts is only 40-50%, which means that blastocyst culture will reduce the viability of embryos. Some hospitals routinely do blastocyst culture, but there is disagreement in the academic community whether to do it or not. It is not necessary to bother with blastocyst culture when half of our patients have ovarian failure and the overall pregnancy rate is maintained at 50%!