[ebb tide]

The eggs that are fertilized become embryos, usually a smaller number. The embryos are examined genetically. Those that are incompatible with life are discarded just as Mother Nature prunes embryos with abnormal chromosomal complements (3 sets rather than two sets etc). The rest are frozen

And just who determines which embryo is compatible with life? Are y'all OK with discarding embryos (remember these are human beings), who carry the Downs syndrome of trisomy 21?

Who made y'all "gods" to determine who lives or dies?

[JayGalt]

Most abnormal chromosomal complements are incompatible with life. Analysis of miscarried embryos show that chromosomal abnormalities are constitute a large number of these spontaneous deaths (~60%). The most common chromosomal abnormality is Trisomy 16 which occurs in 26% of losses. Trisomy 16 is incompatible with life and has never been described progressing more than 11 weeks of gestation.
It would be malpractice to implant such an embryo. There is no need for common sense to conflict with morality.