Pre-implantation genetic diagnosis (PGD) is essentially an alternative to prenatal diagnosis, in which genetic testing is performed on embryos produced by In vitro Fertilization (IVF) before a clinical pregnancy is established. PGD has been mostly applied to woman of advanced maternal age undergoing IVF in order to increase implantation rates, reduce spontaneous abortions and trisomic offspring. This modality of PGD is known as PGD of aneuploidy.

PGD has also been applied to chromosomal disorders, such translocations, in which it has proven to decrease the number of spontaneous abortions while preventing the conception of affected babies.

The number of single gene disorders that have been diagnosed in preimplantation embryos has continued to grow, being the most common ones Cystic fibrosis, fragile X, Myotonic Dystrophy, Thalasaemia, Tay Sachs, and others.