Computer-automated time-lapse analysis has been shown to improve embryo selection by providing quantitative and objective information to supplement traditional morphology. In this multi-centre study, the relationship between such computer-derived outputs (High, Medium, Low scores), embryo implantation and clinical pregnancy were examined. Data were collected from six clinics, including 205 patients whose embryos were imaged by the Eeva(TM) System. The Eeva scores were blinded and not considered during embryo selection. Embryos with High and Medium scores had significantly higher implantation rates than those with Low scores (37% and 35% versus 15%; P < 0.0001; P = 0.0004). Similar trends in implantation rates were observed in different IVF centres each using their own protocols. Further analysis revealed that patients with at least one High embryo transferred had significantly higher clinical pregnancy rates than those with only Low embryos transferred (51% versus 34%; P = 0.02), although patients' clinical characteristics across groups were comparable. These data, together with previous research and clinical studies, confirm that computer-automated Eeva scores provide valuable information, which may improve the clinical outcome of IVF procedures and ultimately facilitate the trend of single embryo selection.

Introduction: For over a decade, the culture of preimplantation mammalian embryos has been approached by one of two culture protocols separated by opposing philosophies. The sequential, two-step protocol is thought to mimic the physiological interaction between specific developmental stages of the embryo and its vicinity within the oviduct and uterus. This protocol is based on the ‘back to nature’ principle that consists of medium renewal approximately midway in the extended culture period; either day-3 or -4 of embryo culture. The opposing system is based on the ‘let the embryo choose’ principal that is analogous to a single step culture medium. By providing the embryo with the appropriate concentration of components as defined through biological standardizations, the embryo is ultimately allowed to determine when and which nutrients and compounds are needed for suitable development. Although the ‘back to nature’ dogma of a two-step protocol is thought to be optimal for zygote to blastocyst development, we now show that blastocyst development and implantation potential are strikingly similar, if not better, in an uninterrupted, non-renewed single step culture medium protocol.