Elective single embryo transfer: the value of cryopreservation

in-vitro fertilization is associated with a high rate of multiple pregnanci es, a consequence of the number of embryos transferred. There is a challeng e in avoiding even twin pregnancies in assisted reproduction, and this can be accomplished with elective single embryo transfer and a good cryopreserv ation programme. In our follow-up study, we analysed all our elective singl e embryo transfers during 1998-1999, In all these cycles at least one embry o was frozen. A total of 127 elective single embryo transfers were performe d with a clinical pregnancy rate of 38.6%, The highest implantation rate wa s obtained with four-cell embryos with < 10% fragmentation (39.8%), Thirty- four patients have delivered (26.8%), one of these being a monozygotic preg nancy. In total 129 frozen-thawed cycles have been achieved in 83 patients. One frozen-thawed embryo has been transferred in 46 cycles with a clinical pregnancy rate of 17.4%, and two embryos have been transferred in 83 cycle s, with a clinical pregnancy rate of 37.3%, Up until now, 66 of 125 patient s in our single embryo transfer programme have delivered or have on-going p regnancies, and 77 still have embryos frozen. The cumulative delivery rate per oocyte retrieval is 52.8% and the twin rate 7.6%, We conclude that elec tive single embryo transfer with a good cryopreservation programme results in very acceptable pregnancy rates with a low risk of twins. This is a cost -effective practice that substantially reduces all risks associated with mu ltiple pregnancies and lowers the cost per delivery.