Day 6 Blast?

[OctaveOne]

I've had 3 cycles of ICSI, the first resulting in our DD, from a day 5, 5AB blast (nothing to freeze)

The next cycle resulted in a BFP, from a day 5, 4AB blast (again nothing to freeze). Sadly MC at 8 weeks.

The most recent cycle also resulted in a BFP, from a Day 5, 4AB blast, but resulted in a chemical pregnancy.

Much to our surprise though, on day 6, we did end up with a 'perfect' 5AA blast - the best graded embryos have produced so far, but the clinic said that the fact that it is a day 6, rather than a day 5 blast meant that it was inferior to any grade of day 5 blast.

There seems to be a lot of disagreement about this in the scientific world - does anybody have any insight into this? I'm quite confused and not keen to rely on this frosty if it is likely to be chromosomal abnormal.

Thanks for your reply - I think the issue is that in a fresh cycle, a day 6 embryo is 'out of sync' with the endometrium, and would probably miss the implantation window.

This is a problem that seems to be overcome by transferring in a frozen cycle, but the clinic are now saying that there is also likely to be a (chromosomal) reason why the embryo only blastulated on day 6, not day 5.

My clinic doesn't do many day 3 transfers (I've never had one), they are of the opinion that an embryo that doesn't make it to blast in the lab would't make it to blast inside the woman either.

Or it could be that it's a girl embryo. I think if it's hatching on Day 6, then that's fine especially if it's an AA grade.

I also read about Day 6's missing the window on a fresh cycle but being very successful in a FET.

Personally, I'd be very excited about this one. But I know that it's easy to overthink it. I had a lovely blast put back but kept on thinking it must be dodgy as he had an odd number of cells on days 2 and 3. So far so good, though.

I had two day 5 blasts and two day 6 blasts after an ivf cycle. I don’t know if the day 5 or day 6 blast became my DS, or what day blast us now a healthy baby growing in my belly. My clinic seemed to treat the day 5 and 6 blasts as being of equal quality and to be used in the same way. Not sure if that helps.

Ahh, congratulations on your pregnancies! Yes, I also think it is a girl embryo, but I worry about the reasons for it being a day 6 blast rather than a day 5.

I want to be excited, but the clinic have got me really worried. They are quite certain that even a 4BB, or 4BC Day 5 blast is a 'better' embryo than a 5AA Day 6 just by virtue of the fact that it blastulated on day 5 not day 6.

My concern is that if the 'best' embryo of the bunch didn't make a pregnancy, then why would the 2nd best fare any better?

twickerhun Were your pregnancies from 2 Frozen cycles?

I've never heard a clinic say a day 6 blast is more likely to have a chromosomal issue...

I've had 2 different clinics freeze day 6 blasts for me, including ARGC which is obviously known for great results

The ARGC day6 blast is still in the freezer and I can't tell you if the other one worked because I had a double transfer of a day 5 and a day 6 which resulted in a singleton pregnancy
But the embryologist there (Create) told me that they would never freeze an embryo that they didn't feel had the potential to be a successful pregnancy, and I trust them on that

I had 6 day 6 blasts in my ivf freeze all cycle (PCOS so lots of blasts). 4 were good enough to freeze and of those 3 of them were chromosomally normal (I had them all tested). My consultant said there would be absolutely no problem putting them back in a fet and in fact they'd had marginally better implantation rates with day 6 blasts! So I wouldn't worry about it.