3 day and 5 day embryos - the facts - Fertility Network UK

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3 day and 5 day embryos - the facts

Corchi profile image

Hi ladies can someone explain to me the importance of embryos reaching 5 days as opposed to 3 days. Is it a lot better? Does it mean 5 days are healthier or doesn’t make a difference? Are 5 day embryos more likely to implant? Any advice would be much appreciated as no one really explains anything !!

53 Replies

Hi, I had the same question and read a lot on the issue. My conclusion is that if you produce lots of eggs, day 5 helps to select the best ones. But if you produce very few, waiting until day 5 will decrease your chances because only 40% will make it to day 5 and after comparing the stat and working out the probabilities, I concluded that you need so many eggs for a high chance of success on day 5. so if you only produce one or 2 eggs, day 3 increases your chances. Because you might not have any survivor at day 5... so your chance to have your own child might die on the way to day 5.

Corchi profile image
Corchi in reply to Lilly12255

Thank you for explaining everything so well. Appreciate it a lot

Hi, I have the same question really too. I had my embryo transfer yesterday at day 3. I only had 1 fertilise which was a step ahead of my previous cycle where I had 2 eggs collected and 100% fertilisation failure. My clinic told me that it was just best to transfer back to it's natural 'environment.' I also have a poor quality embryo at only 3 cells divided whereas my clinic said that it should really be growing at 6-8 cells yesterday. I thought 'what have I got to lose at this point?' because I am further than my last round.

I know deep down this will not work this time around.

Corchi profile image
Corchi in reply to Star26

I pray it does work. Sending courage and baby dust for you. It’s all so hard isn’t it?

Star26 profile image
Star26 in reply to Corchi

Aww thank you so much Corchi. I know it is pessimistic but I know the stats and facts are really against me this time. I did not get this far last time so I am so proud that I have got this far and it is a step in the right direction but it is just confusing as to why I am producing low quality eggs and unsure what to do next with regards to how I can get these eggs of a higher quality and just to produce a few more to give me more of a chance.🤦‍♀️🤦‍♀️

Wishing you all the very best. X

Corchi profile image
Corchi in reply to Star26

Thank you. I feel your frustration. It’s all so difficult and so many questions and unanswered ones too. I am proud of you too! Keep breathing xxx

Star26 profile image
Star26 in reply to Corchi

Awww thank you so much. Xx

Cinderella5 profile image
Cinderella5 in reply to Star26

The theory behind this is that it's better in you than the lab!! Best of luck lovely!xx

Star26 profile image
Star26 in reply to Cinderella5

Thank you so much Cinderella. X

Basically the reason they take embryos to day 5 is to make sure they only have the strongest ones. Basically some day 3 ones can look ok but not make it to day 5 meaning they may not have achieved pregnancy. Ita really just an educated guess of which embryos are strongest.xx

Corchi profile image
Corchi in reply to Cinderella5

So I am presuming day 5 blastocysts are stronger and more likely to succeed than day 3?

Cinderella5 profile image
Cinderella5 in reply to Corchi

Yes as some of the day 3 ones can stop developing by day 4 etc. For instance out of our 5 fertilised and doing ok on day 3, then 3 of them arrested on day 4 and didnt go any further so we were left with 2 day 5 embryos.xx

Is day 6 even better than or no lol? X

Corchi profile image
Corchi in reply to Littlepeax

Gosh I have no idea! Didn’t know they could even get to day 6 outside the wonb

RhinoCat profile image
RhinoCat in reply to Littlepeax

I actually came on an article that said day 6 can achieve live birth but best result comparing day 3,5 and 6 said day 5 blasto had highest success. My clinic are of the opinion that if it can’t make it to day 5 it wouldn’t work 🤷🏼‍♀️ My friend had 4 transfers (3 at day 3) and only 4th with day 5 blasto resulted in a baby .

I guess Day 3 inside you is best chance if it’s going to make it if all else has failed .

For me though :

All 5 of mine made it to day 3, and way I see it ,4 would have ended in miscarriage as only one made it to 5 day blasto.

2 were left to day 6 but not much else was happening.

Every person has their own set of variables which impacts outcomes so for some people 3 is best. At the end of the day ya cant pick, whatever happens happens and ya just gotta hope the clinic with its experience can advise ya 👌🏻🙏🏻

No, unfortunately not, the reason they take them to day 6 is only if they gavent reached the expected grade by day 5. Howeevr I have been here a long time and see some ladies have success with day 6 blastocysts.xx

Corchi profile image
Corchi in reply to Cinderella5

Do they not freeze day 3 embryos?

KiboXX profile image
KiboXX in reply to Corchi

Day 6 embryos are normally the just blastocysts that took longer to get there than day 5 ones. Doesn’t normally affect the quality or make them better or worse.x

Corchi profile image
Corchi in reply to KiboXX

Thanks for explaining

KiboXX profile image
KiboXX in reply to Corchi

No problem 😊

Neither of the two clinics I have used will freeze day 3 embryos. Only those that make it to day 5 or 6 blastocysts and are good quality can be frozen.x

Corchi profile image
Corchi in reply to KiboXX

Interesting. I’m asking because I had 16 eggs fertilize and I was just told the end result which was 9 reached day 5 and were frozen and I’m just wondering what happened to all the other ones !!

KiboXX profile image
KiboXX in reply to Corchi

The other ones will have stopped developing somewhere along the way. You can ask your clinic for a breakdown of the embryo development so you can see where along the five days they stopped.

9 is an amazing number of frozen embryos though! X

Corchi profile image
Corchi in reply to KiboXX

Yes just due to my history of miscarriages waiting for embryo testing seems like a lifetime and I’m just dreading the result if they are all bad that’s why I’m wondering all these things :-) it’s all due to worry!!

KiboXX profile image
KiboXX in reply to Corchi

That’s completely normal! Don’t worry, ask as many questions as you want 😘

I can’t imagine that you won’t get any normal embryos back from your PGS testing, I know it’s difficult but try not to stress yourself until you have the results. I’m optimistic you’ll be pleasantly surprised! 💕

Corchi profile image
Corchi in reply to KiboXX

Thank you such sweet words - so needed

Corchi profile image
Corchi in reply to KiboXX

Do they freeze day 3 embryos though or no? I had to have a frozen transfer

KiboXX profile image
KiboXX in reply to Corchi

They don’t normally. Just day 5 embryos x

KiboXX profile image
KiboXX in reply to Corchi

If you have 9 frozen, they should all be day 5 embryos. They only PGS test once it’s a blastocyst.

Corchi profile image
Corchi in reply to KiboXX

Yes they are all day 5 blastocysts and I am awaiting PGS testing fingers crossed one of them is healthy. I am making myself sick with worry as I’m 40 with 6 previous miscarriages but one miracle baby that was born naturally.

KiboXX profile image
KiboXX in reply to Corchi

I would be the same! I always find it easier to work with numbers so if you think about it, in 7 pregnancies, one was perfect. You have 9 embryos so you should definitely have a perfect one in there as well! 😘

Corchi profile image
Corchi in reply to KiboXX

When you put it like that I feel better and more hopeful thank you! I do still have my nine eggs frozen if all else fails so I shouldn’t complain. I’m just so tired 😓 but thank you for your hopeful and lengthy advice. I don’t know what I would do without this network

KiboXX profile image
KiboXX in reply to Corchi

You’re so welcome. Hope it makes the wait a tiny bit easier.

If it helps, my PGS testing results only ended up taking just over a week to come back. Hoping yours is as quick!x

Corchi profile image
Corchi in reply to KiboXX

Me a month In athens greece :-(

CLDxxx profile image
CLDxxx in reply to Corchi

They froze a day 3 for me and then I got blastocysts. For my frozen transfer they have said they will try and get the day 3 to blastocyst stage.

It’s difficult as everywhere is different but the way I see it is, back when IVF began it was only ever day 2 or day 3s that were the option! Science is amazing but does cause us to worry more I think too 🤯xx

Corchi profile image
Corchi in reply to CLDxxx

Hi CLD how will they get the already frozen 3 day embryo to day 5?

CLDxxx profile image
CLDxxx in reply to Corchi

I think they will thaw it and see if it carries on developing maybe. I really have no idea 🤣I’ll have to ask!

I had no idea this was even possible but they said if it doesn’t progress then they know it’s not the one to use and then I would use another one. Xx

Corchi profile image
Corchi in reply to CLDxxx

Wow super interesting I didn’t even know that was possible! I hope everything goes well for you 💕💕

CLDxxx profile image
CLDxxx in reply to Corchi

Crazy isn’t it! I was only ever doing one cycle so I’m not sure if that makes a difference with what they freeze in case.

Thanks lovely. You too 😘 xxx

My consultant said we shouldn't get too hung up on day 3 or day 5.. basically until recently they never took anything to day 5 they always did day 3 transfers in the UK, but then technology developed and they could culture the blastos. Whilst you could argue a day 5 may have a better chance of implantation they are still in a very foreign environment and have less chance of making it to day 5, whereas a day 3 transfer puts things back where they should be so might develop where it might not have done in the lab.

As the others have said its really a numbers game, if you have loads of eggs clinics tend to try and push to get to day 5 but if you dont have that many a day 3 (or even day 2) transfer is more likely.

One thing I have found on this forum is most people on here seem to get loads of eggs and have day 5 transfers and I think people assume its the norm. I know you have had a number of rounds so you know all about it anyway but for other people reading this there are a lot of people who just don't get many eggs, and quite often don't get to day 5.. it doesnt mean that this is a disaster or things have failed. When I first started I assumed not getting to day 5 was a complete failure and everything was hopeless. The more I read the more I realise anything can happen with any type of quality embryo and the general obsession with getting blastocysts can actually be quite a negative thing for people who arent harvesting many eggs (me!) haha.

xx

Corchi profile image
Corchi in reply to Daisy1245

Thank you 🙏🏼

I have had a day 3 transfer and am now 27 weeks pregnant x

Corchi profile image
Corchi in reply to Emmaxxx

Congratulations!!!

I had 2 eggs fertilised after 7 injected via ICSI (8 eggs collected) and was provisionally booked in for a 2 day transfer. Had the call on the morning to say there was no front runner out of the 2 so they booked me for a 5 day transfer. By day 5, 1 of the embryos dropped out of the race so I had 1 left which was transferred yesterday.

I wasn't given the option of a day 3 transfer, which after reading the reponses was a bit of a risk with such a low number of embryos but I am on my 1 free cycle with the NHS so not sure if that's why 🤷‍♀️

I didn't ask any questions about the quality or the grading as honestly, I don't want to know. I felt so low and upset when was told my AMH levels had dropped significantly last year that I'm doing the self preservation thing. Or trying to at least.

I have been looking online to try and understand the difference between day 2, day 3 and day 5 bit it's all very confusing. This group has helped so much the last few weeks!

Wishing you all the very best xx

CLDxxx profile image
CLDxxx in reply to K84k

It sounds to me that the one who made it to day 5 is a little fighter!

You did the best thing not asking about grades as I think knowing can only cause more worry and confusion - that’s how I feel anyway.

Wishing you all the luck 💗xxx

K84k profile image
K84k in reply to CLDxxx

Thank you and I hope so 🤞🤞

Good luck for your next cycle xxx

CLDxxx profile image
CLDxxx in reply to K84k

Thank you 😘

I think that if you calculate the cumulative probability to achieve pregnancy, it will be higher using only day 3 transfers. But there will be more attempts. So it’s a personal choice. In my case, I have almost zero AHM and 1 egg growing so it’s clear that there will be nothing to transfer on day 5...I am freezing now and will look to transfer on day 3 afterwards

Corchi profile image
Corchi in reply to Lilly12255

Your freezing day 3 embryos ? I’m so confused. I thought day 3 embryos could not be frozen? Sorry I am a newbie

Cinderella5 profile image
Cinderella5 in reply to Corchi

Yes some clinics do freeze day 3 embryos. It's just the preference these days that they take them to day 5. However if you have only 1 or 2 embryos most clinics will do a 3 day transfer....just in case they do better in mum than the lab.xx

Corchi profile image
Corchi in reply to Cinderella5

Ok got it (finally) haha thank you xxx how is your wait going ? Keeping busy in the nice sunshine?

Cinderella5 profile image
Cinderella5 in reply to Corchi

I'm doing ok thanks! Driving myself crazy, wondering what's going on in there....just the usual when in the 2ww!🤯🤪 I have been enjoying the sunshine but that looks to be over today, can't complain as we have been very lucky!xx

Corchi profile image
Corchi in reply to Cinderella5

Just came back the ☀️😝

Lilly12255 profile image
Lilly12255 in reply to Corchi

Yes, that is what I do

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