Avoidance of multiple pregnancy by use of single embryo transfer.

The benefits of single embryo transfer (SET) for both mother and child are evident. Already twin pregnancies constitute a relatively serious problem exemplified by the incidence of cerebral palsy, which will increase significantly as well as a risk for premature birth. Selective embryo reduction in countries where this is allowed may be one way to acutely solve the situation. In the beginning the use of natural cycle in vitro fertilization (IVF) avoided the problem, but with the introduction of controlled ovarian hyperstimulation predominantly by use of gonadotrophins in the early 1980ies the temptation to replace more than 1 embryo at a time became too strong. SET with maintenance of acceptable pregnancy rates can only be achieved if tools (improved morphological criteria, biomarkers, preimplantation genetic screening) to select the most viable/normal embryos are at hand together with improved cryopreservation procedures. In reports from Finland and Belgium already 5 years ago, elective single embryo transfer (eSET) was shown to reach almost the same success rates as double embryo transfer (DET) in selective patient groups (age under 37, good quality embryos). The indications for eSET have increased during the last years. In Finland the initiative came from the IVF clinics while in Sweden a legislative process (in act from January 2003) resulted in the recommendation that eSET should be used in the vast majority of the IVF cycles. In both these Nordic countries around 60% of the transfers are today eSET and the multiple pregnancy rate below 10% with no triplets. From an economical point of view, it is of course evident that multiple pregnancies with the numerous potential complications should be avoided altogether. Countries where IVF is included in the government health insurance will thus most likely show the way towards an even more successful, safer and cheaper treatment of infertile couples in the future.