PGD - Pre-implantation genetic diagnosis enables people with an inheritable condition in their family to avoid passing it on to their children. It involves checking the genes and/or chromosomes of embryos created through IVF to exclude affected embryos. PGS – Pre-implantation genetic screening (also known as aneuploidy screening) involves checking the chromosomes of embryos conceived by IVF or ICSI for common abnormalities. Chromosomal abnormalities are a major cause of the failure of embryos to implant, and of miscarriages. They can also cause conditions such as Down’s syndrome.CGH - is an emerging form of preimplantation genetic screening (PGS) that is used to detect abnormalities in the number of chromosomes in an egg or an embryo.