If the embryo is not doing well or is middle quality they will give it one more day and then check grading. I had a day 5 transfer for a 4AA embryo And my other was 3cc in d5. They left it one more day to see if it would improve and it didn't and got worse to 3cd so they discarded it. Anything with a d they will not freeze.
Hello! I had my feozen at day 5 to get to blastocyst and they did try 4 more at day 6 to give them extra time to get there but they didnt but i had two at day 5. Its the furthest stages they can go xxx