Clinical and laboratory methodology used for ART
continued to evolve and improve, and a surplus of embryos
in excess to what is used or needed for the initial IVF
treatment became increasingly commonplace. During the
early days of IVF, options for the patient with supernumerary
embryos included discarding them, donating them to another
infertile couple, or donating them for use in experimental
research. Although cryopreservation of the embryos was
an option, the freezing and thawing processes often caused
permanent injury to the cells, and most embryos did not
survive. This is best reflected in the very low rates of
pregnancy seen following the transfer of frozen/thawed
embryos throughout the 1980s. Intense efforts to develop
various freezing/thawing techniques and cryoprotective
agents eventually resulted in the first reported human
pregnancy from a frozen embryo in 1983, which
unfortunately ended in premature rupture of the membranes
and termination of pregnancy at 24 weeks of gestation