What do embryo grades mean, and is PGT-A genetic testing worth it?

Embryo grades (like 4AB) describe how a blastocyst looks under the microscope — its expansion stage, inner cell mass and outer layer. Higher grades are associated with better implantation on average, but the grading is subjective, and a lower-graded embryo can still make a healthy baby. PGT-A screens embryos for the wrong number of chromosomes. It may help in selected groups (for example, recurrent pregnancy loss or repeated failed transfers) but the evidence that it improves live-birth rates for everyone is mixed, and it can mean discarding embryos that might have worked. Ask your doctor for the evidence in your situation, and what you'd do differently with the result.