A time-lapse study of pronuclear fading in 39,241 human embryos, following IVF or ICSI. Is it time to fine-tune practice for standard fertilization assessment practice?

Introduction: Current guidelines for embryo assessment propose standard fixed observations to reflect timings of events in the majority of embryos. The Istanbul expert consensus of 2011 advises fertilisation assessment at 17 + /-1 hours post insemination (hpi).