Introducing the Embryo Grading Chart & Ranking Tool: A Game-Changer for IVF Patients
If you’ve ever stared at a list of embryo grades and felt completely lost about what they actually mean for your IVF success, boy do I have a new tool for you!
I’m thrilled to announce the launch of my Embryo Grading Chart & Ranking Tool, a free and accessible resource I created to empower patients navigating embryo transfer decisions. Built using real-world clinical data from over 2,200 single euploid embryo transfers, originally published in a study I co-authored with colleagues at RMA of New York, this tool is the first of its kind to allow users to input embryo morphology grades and receive a personalized ranking based on predicted likelihood of live birth.
👉 Jump straight to the embryo ranking tool, or read the full embryo grading chart below.
My name is Dr. Lucky Sekhon, and I am a practicing REI in New York, and author of the best-selling book The Lucky Egg: Understanding Your Fertility and How to Get Pregnant NOW. I created this tool, because I believe people deserve access to clear, evidence-based fertility education that empowers, not overwhelms, them. I’ve spent years helping patients navigate IVF decisions in my clinic, and I’ve experienced it firsthand as a fertility patient myself. That’s why I wrote The Lucky Egg: to pull back the curtain on reproductive medicine and share the roadmap I wish every patient had. If you are interested in staying up to date with my latest content on fertility, I encourage you to follow me on Instagram or subscribe to my monthly newsletter, The Lucky Egg Drop.
Why Morphology Still Matters—Even After PGT
There’s a common misconception that once an embryo is PGT-normal, all embryos are created equal. But that’s not what the data shows.
Morphology grading, which looks at three key features of the blastocyst stage, still holds predictive value for implantation and live birth. Even among genetically normal (euploid) embryos, the quality of structure can impact outcomes.
Here’s a quick breakdown of the grading system:
| Morphology Component | What It Reflects | Grading Scale |
|---|---|---|
| Expansion Stage | How developed the blastocyst is | 1 to 6 |
| Inner Cell Mass (ICM) | Cells that become the fetus | A (best) to C |
| Trophectoderm (TE) | Cells that become the placenta | A (best) to C |
In our study, embryos with an ICM grade of A had significantly higher live birth rates than those with a C grade (55.6% vs. 32.3%). Similarly, Trophectoderm grades of A or B were associated with better outcomes than Trophectoderm grade C. And embryos that reached the blastocyst stage by Day 5 performed better than those that reached the same stage by Day 6. Importantly, when comparing embryos head‑to‑head, a Day 5 embryo with slightly lower morphology grades will often have higher reproductive potential than a Day 6 or Day 7 embryo with the same, or even better morphology, underscoring that timing of development and morphology need to be interpreted together, not in isolation. My new embryo ranking tool takes all of these factors into account when generating its output for you.
The Embryo Grading Chart
Below is the full embryo grading chart the ranking tool is built on. It ranks all 36 blastocyst grades — every combination of expansion stage 3 to 6, ICM A to C and trophectoderm A to C — from the highest to the lowest relative odds of ongoing pregnancy or live birth, using the component odds ratios published in our study of 2,236 single euploid embryo transfers. Blastocyst day is applied on top of morphology, and that part is explained underneath the chart.
How to read a blastocyst grade
- First character — expansion stageHow far the blastocyst has expanded and hatched. Scale 1 to 6.
- Second character — inner cell mass (ICM)The cells that become the fetus. Graded A (best) to C.
- Third character — trophectoderm (TE)The cells that become the placenta. Graded A (best) to C.
So a 5AB embryo is at expansion stage 5, with an ICM grade of A and a trophectoderm grade of B. Grading describes structure at a single moment in time — it is not a genetic test, and every grade in the chart below still resulted in live births in the underlying study.
| Rank | Grade | Expansion | ICM | TE | Relative odds vs 6AA | Morphology band |
|---|---|---|---|---|---|---|
| 1 | 5AA | 5 | A | A | 1.63 | Higher |
| 2 | 4AA | 4 | A | A | 1.61 | Higher |
| 3 | 3AA | 3 | A | A | 1.61 | Higher |
| 4 | 5AB | 5 | A | B | 1.60 | Higher |
| 5 | 4AB | 4 | A | B | 1.58 | Higher |
| 6 | 3AB | 3 | A | B | 1.58 | Higher |
| 7 | 5BA | 5 | B | A | 1.11 | Higher |
| 8 | 4BA | 4 | B | A | 1.09 | Higher |
| 9 | 3BA | 3 | B | A | 1.09 | Higher |
| 10 | 5BB | 5 | B | B | 1.08 | Higher |
| 11 | 4BB | 4 | B | B | 1.07 | Higher |
| 12 | 3BB | 3 | B | B | 1.07 | Higher |
| 13 | 5AC | 5 | A | C | 1.05 | Moderate |
| 14 | 4AC | 4 | A | C | 1.03 | Moderate |
| 15 | 3AC | 3 | A | C | 1.03 | Moderate |
| 16 | 6AA | 6 | A | A | 1.00 | Higher |
| 17 | 6AB | 6 | A | B | 0.98 | Higher |
| 18 | 5CA | 5 | C | A | 0.74 | Moderate |
| 19 | 4CA | 4 | C | A | 0.73 | Moderate |
| 20 | 3CA | 3 | C | A | 0.73 | Moderate |
| 21 | 5CB | 5 | C | B | 0.72 | Moderate |
| 22 | 4CB | 4 | C | B | 0.71 | Moderate |
| 23 | 3CB | 3 | C | B | 0.71 | Moderate |
| 24 | 5BC | 5 | B | C | 0.71 | Moderate |
| 25 | 4BC | 4 | B | C | 0.70 | Moderate |
| 26 | 3BC | 3 | B | C | 0.70 | Moderate |
| 27 | 6BA | 6 | B | A | 0.68 | Higher |
| 28 | 6BB | 6 | B | B | 0.66 | Higher |
| 29 | 6AC | 6 | A | C | 0.64 | Moderate |
| 30 | 5CC | 5 | C | C | 0.47 | Lower |
| 31 | 4CC | 4 | C | C | 0.46 | Lower |
| 32 | 3CC | 3 | C | C | 0.46 | Lower |
| 33 | 6CA | 6 | C | A | 0.45 | Moderate |
| 34 | 6CB | 6 | C | B | 0.44 | Moderate |
| 35 | 6BC | 6 | B | C | 0.43 | Moderate |
| 36 | 6CC | 6 | C | C | 0.29 | Lower |
Why a 6AA sits below a 5AC. Expansion stage 6 means the blastocyst has already fully hatched. In this dataset, embryos at stage 4 or 5 had higher odds of ongoing pregnancy or live birth than embryos at stage 6, so a top-morphology 6AA ranks below several embryos with a lower-looking ICM or TE grade. The colour band in the chart and the “morphology band” column describe ICM and trophectoderm only, which is why a 6AA is banded “Higher” while still ranking 16th overall.
How blastocyst day changes the ranking
| Blastocyst day | How it is ranked |
|---|---|
| Day 5 | Ranked ahead of every day 7 embryo, whatever the morphology grades. Within the day 5 and day 6 group, the chart above sets the order. |
| Day 6 | Grouped with day 5 embryos and ordered by the chart above. Day 5 blastocysts performed better than day 6 blastocysts. |
| Day 7 | Ranked after all day 5 and day 6 embryos and placed in the lower likelihood band, even with perfect morphology. A day 5 embryo with lower grades will typically outrank a day 7 embryo with the same or better grades. |
What the study actually published
These are the figures reported directly in the study, for 2,236 single euploid frozen embryo transfers in 1,629 patients. Outcome is ongoing pregnancy or live birth.
| Comparison | Published result |
|---|---|
| ICM grade A vs grade C | 55.6% vs 32.3% ongoing pregnancy or live birth (P < 0.001) |
| TE grade A vs grade C | Odds ratio 1.6 (99% CI 1.1–2.3) |
| TE grade B vs grade C | Odds ratio 1.5 (99% CI 1.1–2.1) |
| Expansion stage 4 vs stage 6 | Odds ratio 1.6 (99% CI 1.2–2.2) |
| Expansion stage 5 vs stage 6 | Odds ratio 1.6 (99% CI 1.2–2.3) |
How the relative-odds column was produced. The study reports odds ratios for each morphology component separately — expansion stage, inner cell mass and trophectoderm — not a single published figure for each of the 36 possible grades. The “relative odds vs 6AA” column combines those published component odds ratios into one composite score for each grade, with a 6AA embryo set to 1.00. It is the ranking model this tool uses to order embryos against one another. It is not a published per-grade live birth rate, and it should not be read as one.
Source: Nazem TG, Sekhon L, Lee JA, Overbey J, Pan S, Duke M, Briton-Jones C, Whitehouse M, Copperman AB, Stein DE. The correlation between morphology and implantation of euploid human blastocysts. Reprod Biomed Online. 2019;38(2):169–176. PMID 30579820. Retrospective cohort of 2,236 euploid blastocysts from 1,629 patients undergoing single frozen embryo transfer at Reproductive Medicine Associates of New York between 2012 and 2017.
This chart is for educational purposes and is not medical advice. Embryo grading describes relative likelihood across a group of embryos; it does not predict the outcome of any individual transfer. Please discuss your own embryo report with your fertility team.
Rank Your Own Embryos
Enter the blastocyst day and grade for each of your embryos and the tool will order them for you, applying the same chart above. Add up to 15 embryos.
Embryo Ranking Tool
Select the day and type or select the grade for each embryo, then click ‘Compare Embryos’.
Embryo Comparison Results
Embryos are first grouped by blastocyst day (Day 5/6 vs Day 7).
Morphology is used to rank embryos within each group.
What This Tool Actually Does
The Embryo Grading Chart & Ranking Tool is designed to take commonly reported blastocyst morphology grades and apply evidence-based ranking logic to help you understand which embryos are more likely to result in a live birth. It uses two key factors:
- Blastocyst day — whether an embryo reached full blastocyst stage by Day 5, 6, or 7
- Morphology — specifically the expansion stage, inner cell mass (ICM), and trophectoderm (TE) grades
These inputs are used to sort and compare embryos, giving each one a relative probability of success based on large-scale published outcome data.
Let’s Walk Through an Example
Let’s say you’ve just received your embryo report and you’re looking at three embryos:
- Embryo 1: 5AB (Day 5/6)
- Embryo 2: 3AB (Day 5/6)
- Embryo 3: 5AA (Day 7)
Enter those three into the ranking tool above and it returns them in ranked order: embryo 1 (5AB, day 5/6) first, embryo 2 (3AB, day 5/6) second, and embryo 3 (5AA, day 7) last.
At first glance, you might assume that embryo 3 (5AA) is the best option: it has a “perfect” morphology grade. But this is where blastocyst timing becomes crucial.
Embryo 3 reached the blastocyst stage on day 7, which is considered delayed. Even with excellent morphology, day 7 embryos consistently have lower implantation and live birth rates compared to embryos that reached blast earlier. In fact, a day 5 embryo with a slightly lower grade (like 5AB or 3AB) tends to have a higher chance of success than a top-graded day 7 embryo.
That’s why the tool ranks embryo 1 and embryo 2 ahead of embryo 3, even though their morphology appears less ideal. The tool integrates both timing and morphology into one unified framework that reflects how embryologists and clinicians think about transfer priority in real-world practice.
This doesn’t mean a day 7 embryo with excellent morphology can’t lead to a healthy baby, but when comparing multiple embryos, the earlier-developing blastocysts typically have an edge.
Want to Learn More About Grading?
I’ve written extensively about embryo grading and how it fits into the bigger IVF picture, including how to interpret those cryptic 5AA vs. 6BC labels, and why blastocyst day matters. If you’re just diving into this topic, or need a refresh, check out this deep dive: Embryo Grading and How It Influences IVF Outcomes. I also go into much further detail in my book The Lucky Egg, with a whole chapter devoted to PGT testing and embryo morphology, so please pick up my book if you are interested in learning more.
Why I Built This
Too many patients are handed embryology reports with no real explanation, and expected to make life-changing decisions based on a string of letters and numbers. I wanted to change that.
This tool was born from the same frustration that led me to write The Lucky Egg: a lack of accessible, trustworthy information for people trying to build their families. My goal is to give you the data, context, and confidence you need to make empowered choices, without needing a PhD in embryology.
Whether you're between retrievals, prepping for a transfer, or just trying to understand your options, this tool puts knowledge back where it belongs: in your hands.
Rank your own embryos with the tool above.
Other Free Tools to Try on the Lucky Egg
The Embryo Grading Chart & Ranking Tool is just the latest in a number of different tools I've created over the years and published for free on this site, please check those out as well:
Frozen Embryo Transfer (FET) Due Date Calculator
This calculator helps you estimate the likely timing of your frozen embryo transfer cycle based on your cycle type (medicated or natural), embryo maturity, and other cycle factors: giving you a clearer picture of key dates on your transfer timeline.
AMH Levels by Age Chart
See average AMH levels by age in one chart, then plot your own result against them — an ovarian reserve reference point that gives you an idea of how your ovaries might respond to stimulation when thinking about IVF or egg freezing outcomes.
Beta hCG Level Calculator
Input your beta hCG hormone level and estimated due date, and this tool tells you what week of pregnancy you’re likely in and how your beta hCG compares to typical ranges, especially useful in early IVF pregnancies when levels are being monitored closely.
Egg Freezing Success Calculator
A tool that helps estimate the probability of achieving a certain number of mature eggs or embryos based on factors like age and ovarian reserve, giving you a realistic sense of what to expect from an egg freezing cycle.
Euploid Embryo Predictor Tool
Using age and AMH level, this AI‑based tool estimates your chances of producing at least one genetically normal (euploid) embryo in your first IVF cycle, something many patients ask about before starting treatment.
IVF Due Date Calculator
Once you know your embryo transfer date or expected conception timing, this tool helps project your estimated due date, just like the ones used in obstetrics, but tailored for IVF cycles.
Dr. Lucky Sekhon
Welcome to my fertility blog, the Lucky Egg.
I'm a double board-certified REI in New York City.
My mission is to empower you with practical and scientifically backed information to make the right fertility choices for you!