Preimplantation genetic diagnosis (PGD) is a laboratory test, performed on eggs or embryos during an IVF cycle, that enables couples to check whether their pregnancy may be affected by a chromosomal disorder or an adverse genetic condition. It can be used to screen for many genetic conditions, including single gene disorders and chromosomal abnormalities, decreasing the risk of miscarriage and failed implantation and therefore, increasing the chances of a successful pregnancy.
Many couples ask for PGD to test for aneuploidy (such as Down syndrome). It is thought that a large proportion of early miscarriages may be due to aneuploidy, which increases with the age of the female partner.
Others ask for PGD to test for specific single gene disorders, genetic conditions that run in the family, such as cystic fibrosis or muscular dystrophy.
It can also be used to screen eggs and embryos of individuals who carry a chromosomal translocation, significantly decreasing the risk of miscarriage or birth defects.