After the fertilization process in fallopian tubes, human embryo enters uterus for blastocyst process. Where as in blastocyst transfer, embryo will be cultured outside in the laboratory and when it reaches blastocyst stage that is 5 to 6 days old, it will be transferred into woman uterus. Once it is transferred to uterus, it begins to implant into uterus wall endometrium and undergoes development process. As developed embryo is transferred to womb, natural process of implanting with the uterus wall and development process continues from here. In IVF, 4 days embryo will be transferred where as in blastocyst transfer, 5 to 6 days embryo will be transferred. Hence the success rate of blastocyst transfer is high compared to IVF.