PGD will further expand the number of embryos created but not implanted for pregnancy. This will intensify concerns already present in IVF regarding what should be done with such embryos. Both procedures generate excess embryos that will not be implanted to achieve pregnancy. Currently, federal bans on embryo research demonstrate the government's considerable distaste for this option, albeit those making the policy choice may have had less than complete information. Embryos deselected in PGD will often have anomalies that make them unlikely candidates for donation.
Indefinite preservation seems more a stalling device than a decision.
Preimplantation genetic diagnosis may easily become entwined with attempts at germline gene therapy or genetic enhancement. Genetic enhancement seeks to foster superior or desired genetic qualities rather than simply to remove an impaired condition. Each of these is morally problematic and more controversial than the deselection of seriously impaired embryos. One reason for this expanded definition is that the market for PGD alone may be too small to support the field, producing pressure to extend its prospective clientele. 1,2 Other reasons are inherent in the logic of PGD itself.