The aim of embryo culture is to learn about the embryos and determine which are best and most likely to implant in the womb. ‘Blastocyst culture’ refers to culturing or ‘growing’ embryo from the Day 3 stage to Day 5 / 6. A blastocyst is the next stage in development of an embryo and embryos should have reached this stage by Day 5.
By growing embryos for a longer period of time in the lab, it provides additional information about embryos which can help when selecting the best embryo for Embryo Transfer. Not every embryo will reach the blastocyst stage but those that do have shown they have a greater chance of implanting.