Day 3 vs. Day 5 Transfer
14 Replies
Kodi - August 23

I would like to get some clarification on a Day 3 vs. Day 5 ET. Is it true that if an egg doesn't make it to the blast stage then it most likely won't result in pregnancy if transferred on Day 3? Also, is it better to have an ET on day 3 when only a small number of eggs are available because it is better to have the egg to develop in a woman than in a dish?


Dr Smith - August 24

The primary determinant of whether or not an embryo will continue to grow to the blastocyst stage is the genetics of the embryo, not the environment. You can't change the inherent genetics of the embryo by keeping it in the lab or transferring it to the uterus. The point is moot. Transferring poor quality or arrested embryos to the uterus is a way of bailing out. If the poor embryos were cultured to Day 5, it is likely that they wouldn't make it. The RE doesn't want to deliver the bad news, in case you blame him or the lab for "killing your embryos". Better to transfer them before they arrest and thus avoid the blame game.

The fallacy that poor quality embryos will do better in the uterus than in the lab is based on a single study which culture embryos under suboptimal conditions and concluded that, under their particular suboptimal conditions, the embryos did better in the uterus than in the lab. Duh! If the lab provides optimal conditions to grow embryos to the blastocyst stage, this is not true. That particular line is fed to patients to promote "bailout" Day 3 transfers.

Same is true when there are only a few embryos. With only a few embryos, the probability of not having any blastocysts for transfer is high. Quick, bail out! Day 3 transfer!


jmr67 - September 19

This isn't sounding good! After reading many posts I understand that you prefer transfering Day 5 blastocysts. Having been through one IVF (chemical pregnancy twins) and one cancelled IVF I question my clinic's standard to transfer at Day 3 for most patients. In my positive cycle, I had 11 mature eggs with 100% fertilization. The results were 4 high grade, 4 medium grade and 3 low grade embryos. 2 high grade embryo's were transferred at Day 3, and not one of the remaining embryo's made it to blastocyst stage. My clinic only freezes blastocysts but says most embryo's do not make it that far. After reading many posts I find that may not necessarily be the case. In my particular case we face MF infertility and my age which is now 39. What are the chances in my next cycle if I insist on growing to blastocyst that it will all be a waste?


Dr Smith - September 19

Yes, I prefer blastocyst transfer for a variety of reasons.

Many programs have moved towards freezing only the embryos that reach the blastocyst stage. They are right, after selecting the "best" embryos for transfer on Day 3, only a few of the "left overs" are capable of reaching the blastocyst stage. At 39, you can expect about 20-30% blastocyst development (i.e. 10 fertilized eggs will yield 2-3 blastocysts). In your first cycle, two embryos reached the blastocyst stage - the two that resulted in a chemical pregnancy. The remainder of the embryos failed to develop to blastocysts. About par for the course, at your age. The male factor, if severe, may also reduce the percentage of embryos reaching the blastocyst stage. Now you may be down to 1-2 blastocysts. Could also be zero. Becasue of your age and the contributing male factor, you should prepare for the possibility that there may be no embryos for transfer (not likely, but possible). If that turns out to be the case, would you rather find that out before the transfer or after the two week wait? If you do have 2 blastocysts for transfer, based on your age alone, there is about a 40% live birth rate in your category.


jmr67 - September 19

First of all I'd like to thank you for your invaluable advice! The fact that you take the time to do this just amazes me when I can hardly get my own doctors to call back! 40% doesn't sound too bad. However since I think the MF may indeed be severe I now have another question. I just learned for the first time about the SCSA testing on your site. I have asked 3 other doctors about doing further testing on my husbands sperm and not one has mentioned it. We were thrilled with 100% fertilization on our first IVF/ICSI because his analysis indicated only 5% normal forms. Additionally he suffered a pretty bad chemical exposure overseas as well as contracting visceral Leishmaniasis which kept him in the hospital for a year about 10 years ago on heavy duty meds. Each doctor I asked told me sperm regenerates every 3 months and I didn't have to worry. Now I am concerned that his history would be something that could TOTALLY cause DNA Fragmentation and I know DNA fragmentation doesn't necessarily affect fertilization rate. I would like to have the test. This could mean the world to how far we go with IVF.....what are your thoughts?


4everhopeful - September 21

Hi Dr Smith :)

I was just looking for some feedback really, after reading this post with interest :)

Yesterday I had 8 eggs retrieved, and today we got the 'dreaded' call to say that 6 out of the 8 have fertilized with ICSI... Phew! :P

This time my RE wants us to blast, rather than do a day 3 transfer, which we are really keen on doing too :)

I was just wondering though, that out of 6 fertilized, my age of 33, and FSH of 10, statistically, are we likely to get at least one to put back from that ???
Am obviously very nervous, and I know you don't have a crystal ball (!) but it's going to be a looong weekend!

Also we were told if we blast, they won't A/H them, and would only do that on day 3.... Something to do with being too vulnerable to hatch, does that make sense to you? ???

Assuming we get one at least to the blastocyst stage, does the odds of achieving a positive result increase with b/t?

Many thanx for all your help, and so sorry to bombard you with probably very silly questions!

A very anxious

Nat :)


Dr Smith - September 22

Dear Sleepless in Cyberspace,

Statistically speaking, at 33, you can expect 2-3 of the 6 embryos to make it to the blastocyst stage. However, you've had some failed cycles and its not clear if that was because of an embryo problem or not. Blastocyst transfer is diagnostic as well as therapuetic. If only one or none of the embryos make it to the blastocyst stage on this current cycle, that information, in conjunction with the previous failed cycles, would suggest an embryo problem.

If two or three make it to the blastocyst stage, your chances of pregnancy will be in the 60/40 range, which is as good as it gets for 33.

Hatching blastocyst stage embryos is tricky. You have to use a special technique to "shrink" the embryo away from the protein coat in order to perform assisted hatching. Otherwise, as they said, they are vulnerable to damage. Not everybody knows how to hatch blastocysts. If their embryologist is interested, I can email the protocol.


jmr67 - September 22

Dr. Smith,
Did you see my post above? (Reply #4)..... Based on that do you think the MF is severe? Could the history cause DNA fragmentation? thanks!


Dr Smith - September 26

Oops, sorry I missed it.

Yes, I think there is enough justification for the SCSA test. Although its true that the spermatogenic cycle is about 3 months, that does not take into account any permanent damage that may occurred to the sperm "stem cells" from which all new sperm are derived. Damage to the stem cells from exposure to toxic chemicals that resulted in DNA fragmentation would certainly have an impact of embryo development. In my opinion, the 5% morphology alone is justification for SCSA, but the chemical exposure makes it even more imparative . I would highly recommend your husband undergo the SCSA.


4everhopeful - September 27

Thank you for your reply Dr Smith :)

Sleepless in Cyberspace was about right over the weekend ;D ;D

Well 3 of the 6 embryo's turned into lovely blastocysts! (All 6 were still alive, but 3 were still embryo's, but much better than last time when all our left over embryo's died in the lab over the weekend).

There were 2 bigger blasts and 1 smaller one, and they transfered big blast and little blast because little blasts cells were more even ??? and they said 'he'd' catch up by the afternoon in terms of size!

Unfortunately they wouldn't freeze the 'spare' blastocyst which I was dissapointed about, saying it's more difficult to freeze blasts?
Do you routinely freeze blastocysts? Perhaps it's because there was only 1 :-\

The embryologist said our blastocysts were 'beautiful' and about as good as it gets, so I just have to hope now that they dock with the mothership! If this doesn't work I'm not sure what will...

Many many thanks for all your words of wisdom :)

Nat :)


Dr Smith - September 29

Things sound pretty good. They were correct in telling that the "little" one (of course that's relative statement because they're all pretty tiny) will catch up. Embryos that reach the blastocyst stage expand very quickly. It will undoubtably "catch up" by the afternoon.

It is a little more difficult to freeze blastocyst stage embryos, but I think the real reason for deciding not to freeze the third blastocyst is that your chance of getting pregnant from a single blastocyst FET is pretty small. Yes, I routinely freeze blastocyst stage embryos (actually, only blastocyst stage embryos), but counsel patients against freezing just one (especially a second string blastocyst). We usually follow the "no embryo left behind" doctrine and transfer it with the other two.


4everhopeful - October 8

Dr Smith, thank you so much for your reply :)

It's a shame in the UK that we're only allowed to put back 2 and have to waste one :(

The good news though is that I finally tested positive on Thursday, so these blasts must've been good'uns! I am finally pregnant, and am over the moon!

Am now wondering if there's one or two in there! ;D ;D

Many many thanks for all your helpful advice during my treatments :)

Nat :)


Dr Smith - October 10

Congrats! Cautious optimisim from here on in. Best of luck.


mary5 - October 10

Hi Dr Smith
I have read this thread with great interest as found out today that of my day 3 embryos 6 are at the 6-9 cell stage and they are going to culture them to (hopefully) blast stage. At age 32 what % can I expect to reach blast stage by day 5-6? Of course I am terrified that none will make it and wondered how often this happens but assume if they thought that then would have bailed out and put them back today????

Also for the first time (this is 4th cycle)
they noticed thick zonae when injecting (icsi but no MF) but was also told they could AH if day 3 but they only do mechanical hatching and don't AH blasts due to risk of damage. Now wondering whether chances would have been better to AH them today rather than get blasts that are unable to hatch. What do you think?
anxious mary


Dr Smith - October 10

Out of the 6 embryos, about 2-3 should make it. Relax.

There is a technique to hatch blastocyst stage embryos without traumatizing the embryo. I will be happy to provide the protocol to the embryologist at your lab, should they want it. Have them email me [email protected]



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