RBM Online Volume 15, No 4 October 2007 The Family Federation of Finland, Fertility Clinic, Fredrikinkatu 47, FIN-00101, Helsinki, Finland
In this study, comparable pregnancy results were found after Single Embryo Transfer (SET) and Double Embryo Transfer (DET) when SET was performed with a good quality embryo and the chance of pregnancy was estimated to be favourable. Several prospective randomised trials in conventional IVF patients have demonstrated significantly lower pregnancy rates after SET compared with DET. When transfers with frozen-thawed embryos are included in the cumulative data the live birth rate did not differ substantially between the SET and DET group. Recently Papanikolaou et al (2006) showed better outcome after single blastocyst transfer compared with single cleavage-stage embryo transfer. At the authors’ clinic day 2 or day 3 cleavage stage embryo transfers are routinely performed and the excess good quality embryos frozen.
This strategy enables several embryo transfers from one donor treatment cycle. Thus good cumulative live birth rates can be achieved and, in several cases, also the birth of genetic siblings. The clinic uses Planer controlled rate step freezers. Single embryo transfer (SET) has been the main embryo transfer strategy in the oocyte donation programme at the authors’ clinic since 2000. The primary aim of this study was to evaluate the effect of SET on the clinical outcome in an unselected group of oocyte recipients. A retrospective analysis of the outcome in 142 recipient cycles (116 from anonymous donors; 26 from known donors) was performed. The oocytes from each anonymous donor were shared between two recipients if at least 10 oocytes were obtained. The proportion of SET of all fresh transfers was 77.3%. The clinical pregnancy rate (CPR) was 43.2% and the delivery rate 31.1% per embryo transfer. The outcome was similar in recipients undergoing anonymous and non-anonymous donation.
The delivery rates were similar after SET (30.4%) or double embryo transfer (DET) (33.3%), whereas the twin rate was 0% after SET and 40% after DET. The implantation rate was significantly better (P < 0.01) with good-quality embryos (54.7%) compared with non-optimal embryos (27.1%). Of 152 frozen–thawed embryo transfer cycles, 78.9% were SET. The CPR was 28.3% and the twin rate was 7.1%. In fresh oocyte donation cycles, elective SET can be recommended if the embryo quality is considered good, and always if there is a contraindication for twin pregnancy.