Cleavage stage biopsy significantly impairs human embryonic implantation potential while blastocyst biopsy does not: a randomized and paired clinical trial. *Study showed day 3 embryo biopsy was harmful while day 5 embryo biopsy was not. This showed that a biopsy performed at the blastocyst stage was safe to the embryo and had no untoward effect on IVF outcomes.
