IVF Laboratory
Embryo Grading
Embryo grading is a standardized way embryologists describe embryo development in the IVF lab. It helps your care team decide which embryos are most likely to implant and whether to recommend a fresh or frozen embryo transfer.
What grading does (and does not) mean
Grading reflects appearance and developmental stage on specific days in culture. It does not guarantee pregnancy, and embryos with lower grades can still result in healthy live births. Your age, uterine factors, and genetic testing (when used) also play a major role.
Day 3 vs. Day 5 embryos
Many clinics evaluate embryos on Day 3 (cleavage stage) and again on Day 5 or Day 6 (blastocyst stage). Blastocyst grading often provides more detail about development because the embryo has differentiated into distinct cell groups.
Next steps
If you are planning an embryo transfer, these pages are the most closely related: