Towards single embryo transfer in IVF.

Assisted reproductive technologies have, during the last two decades, managed to overcome a majority of the reasons for infertility in both women and men. Also, infertility associated to a specific couple can generally be successfully treated. The techniques have been proven both safe and cost effective. There is, however, one major shortcoming: an adverse effect in terms of multiple pregnancy, sometimes in the high order. The present communication gives suggestions on how to avoid multiple pregnancy by correct application and improvement of techniques already utilized today. Controlled ovarian hyperstimulation, fertilization and culture procedures, preimplantation genetic diagnosis, freezing procedures and prolonged embryo culture are all techniques and applications which need improvement if the goal of a predominance for singletons with only occasional twins should be reached within a predictable future.