Day 3 of embryo development is crucial for parents using IVF because it marks a significant milestone in the assessment of embryo quality and viability.
That’s because as the embryos continue to develop, they could also be transferred at this point.
You can reach out to us online to learn more about the day 3 embryo transfer timeline, the embryo transfer process that may be best for your situation at this time or any of the steps before or after your egg retrieval.
We can help you with everything from completing your surrogacy planning questionnaire which will lay out how your surrogacy, including the embryo transfer, will look to providing you with a list of fertility clinics close by that you can choose from to create embryos with.
A Day 3 Embryo Transfer Timeline
The day three embryo is transferred to the uterus. The embryo develops into an early stage morula. The morula develops into a blastocyst. The blastocyst hatches, divides and expands. The three steps of implantation occur as the embryo makes contact with the endometrium. The two masses of cells that become the fetus and placenta continue to divide. Human chorionic gonadotropin (hCG) enters the bloodstream. hCG levels reach a point where they can be high enough to detect a pregnancy through a urine or blood test.
Embryo Development at Day 3 [Cleavage Stage]
Day three, otherwise known as the “cleavage stage” for embryos, sees cells continuing to divide after fertilization. They usually consist of 6-8 cells by this point, but are not yet growing in size.
These dividing cells are called blastomeres, they eventually group together to become the morula and are an essential part of the development of the fetus.
Day three is not only an opportunity for your embryos to be tested, they can even be transferred. A day three transfer is an option for your journey if there are not many high quality eggs observed up to this point.
If that’s the case for your situation, then a biopsy for the pre-implantation genetic testing (PGT) evaluates embryos on their number of cells and appearance.
This can determine which embryos are predisposed to disease or inherited mutations
Transfers at this time allow the embryos an opportunity to grow faster due to a better environment for growth found in your surrogate’s body vs. an incubator.
Cleavage Stage Embryo Grading
Embryos are graded similar to PGT, looking at the number of cells and the appearance of those cells.
But PGT determines which embryos are not viable to transfer while embryo grading helps to determine the best embryo to give the best possible chance of becoming pregnant.
Here’s how embryologists can grade day three embryos:
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Cell number: By day three, there should be 6-10 cells. Day three embryos with eight or more cells show a higher live birth rate.
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Cell appearance: Appearance is more subjective based on your professionals grading scale but two key elements are the nuclei within each cell and that the size of each cell is equal.
Another important factor in cell appearance that embryologists look for is fragmentation that can happen when the cells divide.
Up to 20% is allowable but anything past that and the cells lose too much cytoplasm for it to function at its best.
Day 3 to Day 5 Embryo Survival Rate
The number of eggs retrieved does not equal the number of embryos that will be created through in-vitro fertilization (IVF).
As they go through the stages of retrieval, fertilization and growth, they decrease in number. That’s because only mature eggs will successfully fertilize and they grow at different paces.
Between days 3-5, attrition is at its most. Only 30-50% of embryos growing on day three survive to day five.
What are the Chances of Success of a Day 3 Embryo Transfer?
The success rates, factoring in implantation rate, clinical pregnancies and live births, for day three vs. day five embryo transfers was marginal according to a 2017 study.
Another study done by the American Society of Reproductive Medicine didn’t show significant statistical difference for pregnancy rates either.
But implantation rates for day three transfers were 30% compared to 50% for day five transfers. This means that for pregnancy rates to be similar, more embryos have to be transferred on day three.
Talk to your fertility doctor to learn more about their grading system for embryos for a clear understanding for your situation.
By filling out our online form, we can provide you with a list of reputable fertility professionals, like doctors and clinics, that can answer specific questions and help you create embryos.