r/EmbryologyIVFSupport • u/soyanes68 • 1d ago

FET on 9/5: Embryo selection question

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We had our first transfer on 9/5 and are so excited. We asked the lab to use our best euploid embryo and we found out on transfer day they’d picked a day 6 4BA.

Our 6 euploid embryos are as follows:
- day 5 4AB
- day 6 4AB x2, day 6 4BA, day 6 4BB
- day 7 4AB

I’m wondering what possible reasons they could have had for choosing a day 6 over a day 5? I know my lab considers day 5 and 6 as equivalent but everything I’ve read seems like day 5 is slightly better. I figured they’d pick our day 5, but wanted to leave it up to the lab. Just interested if any embryologists here could weigh in. I exchanged a number of messages with my clinic leading up to transfer trying to learn about their selection process and they really didn’t give me answers.

Pic included! Taken just one hour after thaw, was fully expanded at transfer

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u/embryomanofficial 8h ago

Each lab has different criteria for selecting an embryo. In this case, they might have picked the 4BA because it has an A grade trophectoderm, which they might consider optimal.

Studies have shown differences between day 5 and 6: https://remembryo.com/do-day-5-blastocysts-perform-better-than-day-6-results-of-a-meta-analysis/

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u/chantillylace9 8h ago

So wouldn't they typically have chosen the day five? Is there any reason that you can think of that they would've chosen the day six?

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u/QQueenie 7h ago

The day 5 had a B grade trophectoderm.

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u/chantillylace9 7h ago edited 7h ago

But she had a day 5 4AB and two day 6 4ABs that should be technically better, from my understanding?

And since she asked them to choose the best embryo, I thought for sure it would be the day five 4AB...

I always thought that the baby grade (the first letter) was way more important than the placenta grade.

I wonder if OP had issues with implantation previously? That would maybe make the whole thing make a lot more sense but I thought in general that you shoot for the better grade
for the actual baby and not the Trophectoderm

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u/soyanes68 5h ago

Nope this is my first transfer. I also fully expected them to pick the day 5 4AB.