After egg retrieval and fertilization, most clinics eventually share a short update about the embryos that developed. Alongside counts, many reports include a grade. The grade is a visual description from the embryologist, not a diagnosis and not a prediction of pregnancy.
People often receive the grade on a call, in a portal note, or on a printed sheet. The language varies by lab. The job of the grade is the same: to describe how the embryo looked under the microscope at a specific moment so the team can rank which ones to transfer or freeze first.
Day-3 (cleavage-stage) grades
On day 2 or day 3 the embryo is still a cluster of cells. Labs that grade at this stage typically look at three things:
- How many cells are present (even numbers around 6–8 are commonly described as expected for day 3)
- Whether the cells are roughly the same size (symmetry)
- How much fragmentation is visible (small pieces of cytoplasm that have broken off)
Some labs use a simple letter or number scale (A/B/C or 1–5). Others combine cell count with a morphology letter. The exact scale is clinic-specific. A higher grade usually means more even cells and less fragmentation at the time of the assessment.
Blastocyst grades (day 5–6, sometimes day 7)
By day 5 or 6 many embryos, if they continue developing, form a blastocyst: a fluid-filled structure with an inner cell mass (the cells that can become the fetus) and a trophectoderm (the cells that can become the placenta).
A widely used system, often called the Gardner system, produces a three-part grade such as 4AA or 3BB:
- The number (1–6) describes expansion and hatching. 1 is an early blastocyst; 4 is expanded; 5 is hatching; 6 is fully hatched.
- The first letter grades the inner cell mass (A more compact and numerous cells, C fewer or less organised).
- The second letter grades the trophectoderm the same way.
Other labs use good / fair / poor overall labels, or slightly different letter ranges. Ask your clinic which system they use if the report is not self-explanatory.
What a grade is—and is not
A grade is a snapshot of appearance. It does not measure chromosomes. It does not measure how the uterus will respond. It does not guarantee implantation or a live birth. Clinics and patients routinely see higher-graded embryos that do not implant and lower-graded embryos that do. When genetic testing (such as PGT-A) is performed, the chromosome result is a separate piece of information from the morphology grade.
Because grading is partly subjective, the same embryo can receive a slightly different label from a different embryologist or a different lab. That is why the useful question for most people is not “is this an A?” but “how does my clinic rank the embryos I have, and what do they recommend transferring first?”
Keeping the report with the rest of the cycle
The fertilization numbers, the grades, the freeze dates, and the transfer plan often arrive as separate messages. People who track more than one cycle usually want those details in one place so the previous cycle is not overwritten and so they can show the exact report to a partner or a second-opinion doctor later.
Cove lets you log fertilization counts, embryo grades, and the rest of the lab notes next to the medication schedule and appointments for that cycle. You can keep more than one cycle without losing the last one. Download it on the App Store.
For the earlier day-1 numbers that usually arrive before grades, see how the fertilization report is usually structured. For the monitoring visits that happen before retrieval, see IVF appointments and monitoring: what to log. Broader questions about what the app does and does not claim sit on the FAQ.
Grades are one tool the lab uses to organise the embryos you have. They are not the whole story, and they are not a verdict. Your clinic remains the place to interpret the specific report you received.