Published online by Cambridge University Press: 24 December 2019
Preimplantation genetic diagnosis (PGD) was developed in the late 1980s to help couples who are at risk of transmitting an inherited disease to their offspring, as an alternative to prenatal diagnosis during pregnancy. Prenatal diagnosis has the disadvantage that if the diagnosis shows the fetus to be affected, the couple must decide whether they wish to terminate the pregnancy or continue with the knowledge that their child is going to be affected by the genetic disease. PGD offers some of these couples an alternative, as the diagnosis is performed on the preimplantation embryo, and only embryos assessed as being unaffected by the genetic disease are transferred to the patient. The pregnancy is therefore initiated with the knowledge that the fetus is free from the disease, at that moment in time.