Cryopreservation of human embryos as a useful tool for infertile couples.

In order to improve the pregnancy rate per oocyte retrieval while reducing the chance of multiple-gestations, a technique of cryopreservation of human embryos was used for our initial study consisting of 100 infertile patients undergoing in vitro fertilization (IVF) procedure. These patients combined a "fresh" embryo transfer with cryopreservation. The embryos were cryopreserved with 1,2-propanediol. Twenty-nine (29%) patients achieved ongoing pregnancies from the fresh embryo transfer. Thirty patients received a transfer of thawed embryos in a natural cycle. Nine of these patients achieved ongoing pregnancies. Combining these 2 transfers results in a 38% ongoing pregnancy rate. Forty-one patients have yet to receive their frozen embryos. The current success rate in this study indicates that over 50% of the patients in this group can expect to become pregnant by the time all the cryopreserved embryos have been transferred.