Embryo Grading vs. PGT-A: What Each Evaluation Reveals About Your Embryos
During an IVF cycle, the laboratory plays a central role in determining which embryos are best suited for transfer. Two of the most important tools available are embryo grading and preimplantation genetic testing for aneuploidy, known as PGT-A. Understanding what each assessment measures helps patients approach the process with greater clarity.
What Embryo Grading Tells Us
Embryo grading is a visual assessment performed by trained embryologists who evaluate the structural appearance of an embryo under a microscope. At the blastocyst stage, grading accounts for the degree of expansion, the quality of the inner cell mass, and the organization of the trophectoderm. Higher grades suggest a more morphologically developed embryo, which has historically correlated with improved implantation rates. However, embryo grading reflects appearance only. It cannot determine whether an embryo carries the correct number of chromosomes, a key factor in both implantation success and miscarriage risk.
What PGT-A Adds to the Picture
PGT-A is a form of genetic testing performed on a small biopsy taken from the trophectoderm of a blastocyst. Trophectoderm is the outer layer of cells on an early embryo that become the placenta. The analysis examines all 23 pairs of chromosomes to identify embryos that are euploid, meaning chromosomally normal, versus those that are aneuploid, meaning they carry an abnormal number of chromosomes. Chromosomal abnormalities are among the leading causes of failed implantation and early pregnancy loss. PGT-A is particularly relevant for patients of advanced maternal age, those who have experienced recurrent pregnancy loss, or those with a history of failed IVF cycles. It is also an important option for individuals using donor eggs or gestational carriers, and for LGBTQ+ patients building their families through third-party reproduction.
Using Both Tools Together
Neither assessment alone tells the complete story. An embryo can receive a high morphological grade and still be aneuploid, just as a lower-graded embryo may test as chromosomally normal. When used in combination, embryo grading and PGT-A provide a more comprehensive basis for selecting the embryo most likely to result in a healthy pregnancy. The decision to pursue genetic testing is individualized and depends on clinical history, age, and personal priorities — all of which are best evaluated in consultation with a reproductive specialist.
To learn more about IVF, embryo genetic testing, and whether PGT-A may be appropriate for your care, schedule a consultation with the team at NYU Langone Fertility Center.
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The NYU Langone Fertility Center Blog
At NYU Langone Fertility Center, our first job is to support our patients as they become educated about their reproductive health and fertility treatment options. Our blog connects patients with the most up-to-date information, technologies, and insights into fertility care. From egg freezing to IVF to third-party reproduction options, we explore every facet of assisted reproductive technology and empower patients with the knowledge they need to navigate their family building journeys.