ABSTRACT
Selection of human embryos for transfer following in vitro fertilization (IVF) programs is routinely based on pronuclear or embryo morphology and cleavage rate.1 Despite numerous attempts to develop embryo scoring techniques that can predict embryo viability, implantation rates remain low.1 Not all embryos with good morphology will implant, and fragmented embryos can develop to the blastocyst stage in vitro.2 In fact, embryo selection based on morphology fundamentally eliminates only severely impaired embryos. To achieve acceptable pregnancy rates more than one embryo is routinely transferred, with an unavoidable risk of multiple gestations. Micromethods for assessing the metabolism of embryos were developed in order to improve the selection of embryos with the best developmental potential.
