Preimplantation Genetic Diagnosis is a method of identifying chromosomal abnormalities before implantation of the embryo. The procedure is conducted after the egg has been fertilized in vitro, but before the developing embryo is transferred to the womb.

PGD involves physically removing 1 or 2 such cells from the embryo. Even though cells are removed, the embryo itself is left undamaged. Using this process, embryos can be checked for common genetic diseases such as Down’s syndrome before they are transferred, helping to reducing the tragic outcome of a child with a major birth defect. PGD is typically recommended for couples when one or both parents are a known carrier of a genetic disease.