Hi MeridithD.

I have read some medical research on the matter and it indicated that blast transfer is more successful because of more or less the explanation you have given. My success with blasts is a testament of this. However, growing blast require better lab environment than day 3 and if your clinic is not equip with the right "stuff" your embies might not have their proper chances. Also not all people are suitable for blasts as they are harder to cultivate and many FS prefers to give the good day 3 embies a go "in the natural evironment".

I had very excellent day 3 (one after thawing was at 10 cell stage, the others at 8 or 9) but I still had an BFN.