The culture conditions, or the quality of the sperm or egg cells can result in the embryo not continuing its development towards becoming a blastocyst.
The possible causes that cause the embryo to block its development are:
Fragmentation of double-stranded DNA that the egg is not able to repair, therefore, the embryo will not be able to activate its genome..
Altered FISH will lead to an increase in aneuploid embryos.
Poor oocyte quality, post-ripe eggs, eggs with endoplasmic reticulum or altered polar bodies may prevent the embryo from continuing its development.
Genetic or chromosomal alterations present in the embryo that will make it unable to activate its genome.