There is a lot of planning and research that goes into gestational surrogacy. Many thoughts about surrogacy revolve around emotions and relationships such as the heartbreak of infertility and the importance of trust and a connection between the surrogate, the agency, and the intended parents. But one of the most essential factors to understand is the science behind successful surrogacy. This includes the ability to produce embryos and assess them for viability.
Accurately grading embryos has gotten increasingly important over the years. When IVF technology was newer, multiple embryos were often placed in the woman’s uterus. The thought was the more placed, the better the chances of a successful pregnancy, which to a degree was true. Unfortunately, it also increased the likelihood of multiple births with all the inherent risks of miscarriage, premature delivery, and defects.
Today’s philosophy is to examine the embryos closely and select those that appear to be the most viable for implantation. Here’s how that is done.
Typically, embryos are graded at three days and at five days to determine if their development is progressing as expected and will be healthy enough to survive freezing or a pregnancy.
Embryos are graded on a scale of one to four. Three-day embryos are called cleavage-stage embryos. Five days after fertilization, they are referred to as blastocysts. Day three embryos are examined under a microscope to see if the cells have divided as they should. They are graded based on the number and uniformity of the cells.
Normally, only those graded one or two will be implanted. Sometimes grade three will be used if other factors made it appear viable or if grade one or two are not available.
At five days, the embryos are graded again, this time to ensure the embryos are continuing to develop normally. Now they are graded from A to D. The “perfect” embryo would be rated 4AA, but there are many factors that go into determining quality and viability. Your reproductive endocrinologist will monitor them closely to assess which ones stand the best chance of resulting in a successful pregnancy.
Accurate grading is important to both intended parents and gestational surrogates because they are both invested in a successful outcome. This topic is likely to be broached in the contract stage when the parties agree on how many embryos will be implanted and discuss a selective reduction. Embryo grading is indeed a crucial aspect of the science behind successful gestational surrogacy. The grading process allows reproductive specialists to assess the quality and viability of embryos before implantation, increasing the chances of a successful pregnancy while minimizing the risks associated with multiple births.
Embryo grading typically occurs at two stages: three days after fertilization (cleavage-stage embryos) and five days after fertilization (blastocysts). Let’s delve into the grading process at each stage:
Cleavage-stage embryos (graded on a scale of one to four): At the three-day mark, embryos are examined under a microscope to determine if they have undergone the appropriate cell division. The number and uniformity of cells are considered in the grading process. Generally, only embryos graded as one or two are selected for implantation. Grade three embryos may be used under certain circumstances, such as if other factors indicate viability or if grade one or two embryos are unavailable. Blastocysts (graded from A to D): By the fifth day, the embryos have developed into blastocysts. At this stage, grading becomes more nuanced, using a combination of two criteria: the expansion of the embryo (represented by a letter from A to D) and the quality of the inner cell mass and the trophectoderm (represented by a second letter from A to C). The ideal embryo, often referred to as “perfect,” would be graded as 4AA, indicating excellent expansion and quality. However, it’s important to note that grading involves various factors, and the specific grading system may differ slightly between clinics or specialists. The reproductive endocrinologist closely monitors the embryos to determine which ones have the highest chance of resulting in a successful pregnancy.
Accurate grading is essential for both intended parents and gestational surrogates as they share the common goal of a successful outcome. During the contract stage, discussions about embryo transfer and the possibility of selective reduction (if multiple embryos implant) may take place. These conversations help establish mutual understanding and ensure that the parties involved are aligned in their expectations.
If you have further questions about the science of embryo grading or any other aspect of gestational surrogacy, it is advisable to refer to previous posts or reach out to Surrogate Solutions or a reproductive specialist for more information.
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