HUMAN EMBRYO CRYOPRESERVATION. “Embryo cryopreservation is … a component of in vitro fertilization (which generally also includes ovarian hyperstimulation, egg retrieval and embryo transfer) … a study of 23 countries that almost 42,000 frozen human embryo transfers were performed during 2001 in Europe.”
http://en.wikipedia.org/wiki/Embryo_cryopreservation