Tahli Well, he was a B2 on day 5. If they'd grown him out to day 6 then presumably he would have reached a higher grade. I've heard of early blastocysts resulting in a pregnancy, I think it's when you're talking about morulas that it gets really sketchy.
The embryologist at Genea told me they don't freeze any blastocysts that haven't reached expanded blast by day 6 so I always assumed anything frozen must be pretty good but obviously other clinics are different. It's not terribly straightforward is it?