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 a 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 a 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 selective reduction.