ABSTRACT
Embryo cryopreservation has a long and established history and is the most successful option at present in terms of achieving a desired pregnancy at a later date. However, it is applicable only to couples in a stable relationship and there are ethical concerns about long-term storage of embryos. More recent options of cryopreservation of oocytes or ovarian tissue are promising alternatives, particularly for single women. It must be emphasized, however, that the success rates are currently significantly below that for embryo cryopreservation, and there have been no recorded pregnancies as a result of transplantation of cryopreserved ovarian tissue to date.
