for my case. my embryos reaches blastocyst stage in day 5 & did the transfer. some of my eggs doesnt make it to blastocyst stage so they threw it. i was told by a fren that this embryos came in grading, so was curious & approached the embryologist what is my embryo grade that have been transferred in me. It was a C. She did explain the grading is only within their lab but not the percentage in pregnancy. doesnt mean you have A, it will stick thou. I was disheartened at first, but guess what i got BFP!