Is blastocyst embryo transfer (ET day 4-5 ) the best day to transfer?

By keeping the embryos in culture until day 4 or 5, we can narrow the choice down by assessing which embryos develop to blastocyst; a stage an embryo must reach before it can implant successfully.

Blastocyst transfer (day 4-5) is always advised when we have a choice of embryos from a group. We know that not all embryos have the capacity to reach the blastocyst stage so this is an important selection tool, to give you the best chance of success. The potential of embryos on day 2 or 3 is hard to predict, yet if the number of available embryos is small (perhaps one or two), depending on your situation, we may advise to transfer earlier, on day 2 or 3.