Percentage of embryos make it to blastocyst stage

[bows&ribbons]

Do you know what percentage of embryos make it to blastocyst stage and when they do, are the less likely to be abnormal or are half of those still abnormal?

[Carole]

Dear bows & ribbons,
I would expect at least half of the embryos to proceed to blastocyst stage. Whether they proceed to blastocyst stage is a function more of their overall health and not necessarily due to an underlying genetic abnormality. In fact, triploid embryos which have a complete extra set of chromosomes (also called 3PNs) can produce lovely looking blastocysts that then fail thereafter and never result in an ongoing pregnancy. So progress to blastocyst and genetic normality are not necessarily correlated. Hope this helps.
Carole

[bows&ribbons]

Is there any known risk associated with having embryos live in the culture for that long? SHould that affect the baby to be developed from that??

[Carole]

I am not aware of any reputable claims that culture to day 5 using commercially prepared culture medium designed to support the nutritional needs of the embryo from cleavage stage to blast stage has caused any risk to the baby. I think day 5 culture is actually a better way to do IVF, because you can select for the most viable embryos in culture. Also when you are returning a day 5 blastocyst embryo to the uterus, that embryo is more ready to implant than a cleavage stage embryo which normally would still be developing in the fallopian tubes and not be in the uterus yet.
Carole

[jils04]

Thanks Carole for the info as well. I always new blast does not necessarily = great transfer.

[bows&ribbons]

Hi Carole,
I recently had 31 follicles retrieved, I believe there were 29 eggs and all were fertilized naturally. Of those, only 9 made it to PGD on day 5 and it was at a top NY clinic/lab. Do you think I should be concerned about their culture medium. They said that my loss was normal (i lost 20 eggs waiting till day 5) and similar to that experienced by young donor patients. I am a bit disappointed bc of those 9, 5 were normal and 4 of them boys.

[Carole]

I know it is disappointing to have so few embryos after such a promising start but it is not that unusual. We often see an attrition rate at each step as you experienced. Typical results are 70% fertilization and of those, I expect 70% to go on to blastocyst stage. So based on these expectations, your results aren't that atypical. And selecting for gender adds another attrition step because you are likely to have only 50% of the gender you want. (Not to mention the possible loss of embryos from "no signaL' or other assay issues that can prevent an embryo for being eligible for transfer.) So, in my opinion, there is no reason to think that the culture medium was suboptimal. I hope that some of the normals were girls so you had a transfer. Wishing you all the best, Carole


Hi Carole,
I recently had 31 follicles retrieved, I believe there were 29 eggs and all were fertilized naturally. Of those, only 9 made it to PGD on day 5 and it was at a top NY clinic/lab. Do you think I should be concerned about their culture medium. They said that my loss was normal (i lost 20 eggs waiting till day 5) and similar to that experienced by young donor patients. I am a bit disappointed bc of those 9, 5 were normal and 4 of them boys.

[bows&ribbons]

But I didn't get 70% go on to blastocyst stage. Only 9 out of 29 ...but my RE said that what i experienced was totally normal and to be expected. I only had 1 normal female that made it to blast and she is frozen. My RE also said that he has only experienced 50% success rate (which he believes is higher than for day 3 biopsy embryos) with the frozen 5 day biopsy transfers.

[Carole]

But I didn't get 70% go on to blastocyst stage. Only 9 out of 29 ...but my RE said that what i experienced was totally normal and to be expected. I only had 1 normal female that made it to blast and she is frozen. My RE also said that he has only experienced 50% success rate (which he believes is higher than for day 3 biopsy embryos) with the frozen 5 day biopsy transfers.

You misunderstood me. The 70% is of the number that got to cleavage stage, which is a portion that get fertilized. So if 70% of you 30 fertilize, that's 21. If 70% of 21 cleave, that's 15, if 50% of those go to blast, that's 7 and if half of those are the gender you want, that's only 3-4 embryos, pretty much what you experienced. large egg numbers to start doesn't mean that all the eggs are developmentally capable. In fact, it seems like 10-12good eggs is what most of us can expect. the "extra eggs" even if they extrude a polar body (one sign of maturity), they may not be completely mature in their cytoplasm and able to tak ethe developmental program the whole way to blast. Hope this helps. Carole