Survey on cryopreservation.

In this survey on cryopreservation of human embryos and oocytes, the results from 24 groups that reported replacements of cryopreserved embryos by the end of 1986 were summarized. So far 163 pregnancies have been reported, 65 children have been born, and 61 pregnancies were ongoing at the time of tabulation. The real impact of freezing and thawing of human embryos and oocytes in the treatment of infertility will require a careful analysis of all factors influencing the cryopreservation.