Zavos is quite correct that chromosomal damage is very obvious, and can be screened out very simply. At a purely morphological level, cleavage of the embryo is not normal and that embryo must be discarded. Chromosomal abnormalities arise because remodelling and reprogramming of the somatic chromatin is incomplete. Fine with animals, not with humans. Which is why karyotype screening is such an essential component of Zavos's proposal.
Histones cause the DNA to be wrapped up into tightly bound structures called chromatin.
When exposed to the egg cytoplasm this structure begins to decondense and reprogram. This is also screenable from karyotype screening. This is a major cause of developmental abnormality. When any of the 30 mammalian imprinted genes are not properly reprogrammed, you get developmental abnormalities. The methylation state of these 30 genes must be screened for.