pre-implantation genetic diagnosis (pgd or pigd) refers to genetic profiling of embryos prior to implantation (as a form of embryo profiling), and sometimes even of oocytes prior to fertilization. pgd is considered in a similar fashion to prenatal diagnosis. when used to screen for a specific genetic disease, its main advantage is that it avoids selective pregnancy termination as the method makes it highly likely that the baby will be free of the disease under consideration. pgd thus is an adjunct to assisted reproductive technology, and requires in vitro fertilization (ivf) to obtain oocytes or embryos for evaluation. the term preimplantation genetic screening (pgs) is used to denote procedures that do not look for a specific disease but use pgd techniques to identify embryos at risk. the procedures may also be called preimplantation genetic profiling to adapt to the fact that they are sometimes used on oocytes or embryos prior to implantation for other reasons than diagnosis or screening.page 205 in:  procedures performed on sex cells before fertilization may instead be referred to as methods of oocyte selection or sperm selection, although the methods and aims partly overlap with pgd. ==history== in 1967, robert edwards and richard gardner reported the successful identification of the sex of rabbit blastocysts. it was not until the 1980s that human ivf was fully developed, which coincided with the breakthrough of the highly sensitive polymerase chain reaction (pcr) technology. handyside and collaborators' first successful tests happened in october 1989, with the first births in 1990 though the preliminary experiments had been published some years earlier.{{cite journal |author=coutelle c, williams c, handyside a, hardy k, winston r, williamson r |title=genetic analysis of dna from single human oocytes: a model for preimplantation diagnosis of cystic fibrosis |journal=bmj |volume=299 |issue=6690 |pages=22â4 
Eugenics In_vitro_fertilisation Medical_genetics Prenatal_sex_discernment