[Cryopreservation of human embryos. A new dimension of in-vitro fertilization]

The use of multiple embryo-transfers during the procedure of in-vitro fertilization increases the clinical pregnancy rate but also the rate of multiple gestation. To reduce this risk cryopreservation techniques can be used for storing excess embryos. These can be used for replacement in spontaneous ovulatory cycles or could be used for transfer to a woman who cannot produce her own gametes. Reservations concerning the use of cryopreservation techniques are the risk of cryo-injury, the unknown risk of birth defects, the fear of failure in the mechanical support systems and the legal status of the embryo. Several committee considerations and recommendations are cited.