Development of a blastocyst is a big step for a tiny new organism and makes it possible for more growth and change to come.
A blastocyst, which is the second stage of a fertilized egg after the morula phase, is getting too big for the cellular constraints that kept it safe. Just like you, though, the new individual isn't ready for the big world—it needs a safe place where it can grow and, well, have more food.
Once fertilization has happened it is only about 7 days before the new life implants into the wall of the uterus (which is the womb), but changes have to happen to make sure all goes well, and a few of them are pretty dramatic. While it's not technical terminology, one way to help remember the stage is that the group of cells looks like it has blasted out of a cyst.The biggest advantage of Blastocyst Culture and Transfer method is that it significantly reduces the risk of multiple pregnancies. Also, the pregnancy and implantation success rate is higher in this technique because it is easy to determine the robust embryos after developing for 4-6 days hence only the competent embryo are transferred to uterus.