The embryo freezing programme at Groote Schuur Hospital. First results

'Surplus' embryos from 28 patients on the in vitro fertilisation programme at Groote Schuur Hospital were frozen for transfer in later cycles. Depending on the stage of the embryos, either propanediol or glycerol was used as a cryoprotectant. In 20 patients embryos survived the thawing procedure and were transferred. Five pregnancies resulted, 2 twin and 3 singleton. The pregnancy rate per embryo transfer in this group of patients in thus 25%. The pregnancy rate per freezing procedure is 19.2%.