The waiting period after an embryo transfer can feel like an eternity. Some people find it helpful to keep themselves occupied, while others prefer to imagine what might be happening with their embryo. To give you an idea of the process, we’ve outlined the stages of embryo development day by day. Embryo development starts with the union of he sperm and egg. It is a general term used to describe the cluster of cells that eventually becomes a foetus. However, there are several stages of embryo development that occur before this point:
Day 1: Zygote– the fertilised egg
Day 2-3: Two-cell to eight-cell stage: the embryo after its first few cell divisions, also called cleavage stage.
Day 4: Morula: the embryo that now has about 10 to 30 cells that continue to divide- its name comes from the fact it looks like a mulberry!
Day 5-7: Blastocyst: the mass of cells that now has two defined layers- the trophectoderm (outer cells that eventually become the placenta) and the inner cell mass (inner cells eventually become a baby).
During IVF, embryos are often at the blastocyst stage when they are transferred to the uterus, whether it’s in a fresh cycle, it’s possible that the most developed embryo on the transfer day is not yet a blastocyst. In this case, a morula-stage embryo may be transferred with the hope that it will continue to develop inside the uterus., it must go through these stages within the uterus before it can implant.
For an embryo to successfully implant in the uterus, it must go through the development stages of cleavage, morula, and blastocyst. This means that even if a day-3 embryo is transferred, it must go through these stages within the uterus before it can implant.
What are the stages of Implantation?
Implantation is a complex process that involves the blastocyst embryo attaching itself to the wall of the uterus. Scientists have identified three key steps in this process:
- Apposition: The blastocyst comes into contact with the uterine wall and forms an initial, loose connection. Think of this as the embryo positioning itself for implantation.
- Adhesion: The connection between embryo and the lining of the uterus becomes stronger.
- Invasion: The outer cells of the blastocyst begin to penetrate the uterus.
The stages of implantation occur over a period of two to three days after the embryo has hatched. It is only after implantation is complete that the pregnancy hormone (hCG) is released by the embryo and can be detected in the mother’s blood stream and urine, which ca be detected by at-home urine pregnancy test.
What happens after an embryo transfer, day by day?
The process that follows an embryo transfer, whether it is a fresh or frozen embryo, is generally the same. The main difference comes from whether the doctor transfers a pre-blastocyst (such as a “cleavage stage” or “day-3 embryo”, which means it has developed for three days after fertilisation) or a blastocyst, which can be a day-5, day-6, or day-7 embryo.
What happens after a blastocyst day 5/6/7 embryo transfer?
Day 0: Embryo transfer: The embryo is transferred to the uterus.
Day 1-2: Embryo evolution: The embryo hatches (if it wasn’t already (and continues to divide and expand.
Day 3-5: Apposition, adhesion, and invasion: The embryo makes contact with the endometrium, connects to it and implants.
Day 6+: Cell division and hCG production: Cells that will become the foetus and placenta continue to divide, and the pregnancy hormone (hCG enters the bloodstream).
Day 7: Pregnancy Test: hCG levels may be high enough to detect pregnancy with a urine or blood test. (Your clinic will typically wait a little longer to schedule a blood test for most accurate results).
What happens after a cleavage stage day-3 embryo transfer?
Day 0: Embryo transfer: The embryo is transferred to the uterus.
Day 1: Embryo development: The embryo develops into an early morula.
Day 2-3: Embryo development: The morula develops into a blastocyst.
Day 4: Embryo evolution: The blastocyst hatches (if it wasn’t already) and continues to divide and expand.
Day 5-7: Apposition, adhesion, and invasion: The embryo makes contact with the endometrium, connects to it and implants.
Day 8+: Cell division and hCG production: Cells that will become the foetus and placenta continue to divide, and the pregnancy hormone (hCG) enters the bloodstream.
Day 9: Pregnancy Test: hCG levels may be high enough to detect pregnancy with a urine or blood test. (Your clinic will typically wait a little longer to schedule a blood test for most accurate results).
How soon can a pregnancy test be taken after an embryo transfer?
The timing for taking a pregnancy test after an embryo transfer can vary depending on certain factors. Typically, clinics schedule a pregnancy blood test, also known as a beta test, around 9-13 days after a transfer. However, if you want to use an at-home pregnancy test, its important to take into account whether a trigger shot was used during the pre-transfer protocol as it could contain hCG that could affect the test results. If a trigger shot was used, it’s recommended to wait 14 days post-trigger or until the scheduled blood test.
Alternatively, some people in the fertility community prefer to “test out” the trigger shot by taking daily tests to monitor hCG levels from the trigger shot. Additionally, whether the transferred embryo was a blastocyst or pre -blastocyst, as well as an individual’s variations in development, can also influence when hCG levels become detectable on a test.
Generally, for a day-5, day-6, or day-7 embryo transfer, it’s possible to test 7 days after the transfer and retest 2 days later if the results are negative. For a day-3 embryo transfer, it may take a couple of extra days for hCG levels to be detectable on a test.
