My name is Dr. Lucky Sekhon, and I am a Reproductive Endocrinologist & Infertility specialist and author of the Lucky Egg. One of the most common questions I hear from patients considering IVF is a version of the same worry: “will any of my embryos actually be normal?”
This page is my attempt to answer that properly — first by explaining the difference between euploid and aneuploid embryos and why it matters so much, then with a free predictor tool that estimates your own chance of producing at least one euploid embryo in a first IVF cycle, based on your age and AMH level.
Euploid vs aneuploid: what the difference actually is
A euploid embryo has the normal number of chromosomes — 46, arranged in 23 pairs. An aneuploid embryo has too many or too few. One extra copy of a chromosome is a trisomy; one missing copy is a monosomy. You may also hear about mosaic embryos, which contain a mix of normal and abnormal cells — more on those below.
That single difference matters more than almost anything else in IVF. The large majority of aneuploid embryos simply do not implant, or they miscarry early — often before a pregnancy is ever confirmed. A handful of specific aneuploidies are compatible with a continuing pregnancy, of which trisomy 21 (Down syndrome) is the one most people have heard of. But the common outcome of an aneuploid embryo is not a baby.
This is why so much of fertility medicine circles back to chromosomes. When people talk about “egg quality,” this is, in large part, what they mean.
Why euploid rates fall with age
Eggs are not made fresh. You were born with all of them, and each one has been paused mid-division for as long as you have been alive. When an egg finally completes that division — at ovulation, decades later — it has to pull its chromosome pairs apart cleanly and discard exactly half.
The machinery that holds those pairs in place degrades over time. The longer an egg has been waiting, the likelier it is to separate its chromosomes unevenly, and the result is an egg with a missing or extra copy. This is why aneuploidy is overwhelmingly driven by the age of the egg, not by the age of the sperm or the uterus, and it is why a 42-year-old using donor eggs from a 25-year-old has the euploid rate of a 25-year-old.
The scale of this is well documented. The largest analysis of its kind — a review of 15,169 consecutive embryo biopsies published in Fertility and Sterility, and conducted at Reproductive Medicine Associates of New York, where I practise — found that aneuploidy stayed relatively stable through the late twenties and early thirties, then climbed steadily from the late thirties onward. The most favourable window in that data sat between roughly ages 26 and 30.
What that means in practice is that the number of eggs retrieved matters, but so does the proportion of them likely to be chromosomally normal — and the second number moves against you faster than the first.
See the full data table and where these numbers come from
| Age | AMH 0.5 ng/mL | AMH 1.0 ng/mL | AMH 2.0 ng/mL | AMH 4.0 ng/mL |
|---|---|---|---|---|
| 29 | 69% | 77% | 89% | 94% |
| 30 | 69% | 76% | 89% | 93% |
| 31 | 66% | 74% | 87% | 92% |
| 32 | 67% | 74% | 88% | 92% |
| 33 | 66% | 73% | 87% | 91% |
| 34 | 65% | 73% | 85% | 91% |
| 35 | 63% | 71% | 83% | 90% |
| 36 | 59% | 69% | 81% | 88% |
| 37 | 57% | 69% | 81% | 87% |
| 38 | 53% | 67% | 80% | 85% |
| 39 | 49% | 63% | 76% | 82% |
| 40 | 38% | 50% | 65% | 72% |
| 41 | 35% | 46% | 59% | 67% |
| 42 | 31% | 40% | 49% | 59% |
| 43 | 27% | 34% | 43% | 51% |
| 44 | 16% | 24% | 30% | 37% |
Where these numbers come from
These are not published data. They are the output of this tool’s own prediction model, captured on 2026-07-26. No published study reports these figures, and they should not be read as one.
The model is a stacked ensemble binary classification model (H2O), trained on clinical IVF outcomes. On its own validation data it scores an AUC of 0.84 and a mean squared error of 0.14 — useful, but well short of certainty for any individual. The training dataset is not public.
The model is reliable only between ages 29 and 44, because that is where its training data is concentrated. Outside that band its accuracy falls off sharply, which is why the calculator does not accept those ages.
One quirk worth naming: the predicted chance rises slightly from age 31 to 32 at every AMH level, and there are smaller rises around ages 30, 34 and 38. That is noise in the model, not a real finding — fertility does not improve at 32. We have plotted the values exactly as the model produces them rather than smoothing the curve, because showing you the model as it actually behaves is more honest than showing you a tidier line we invented.
This chart is a snapshot. If the model is retrained, these values may change.
What PGT-A can — and cannot — tell you
Preimplantation genetic testing for aneuploidy (PGT-A) is how we find out whether an embryo is euploid. Around day 5 or 6, an embryologist removes a few cells and sends them for chromosomal analysis. Embryos are then reported as euploid, aneuploid, or mosaic.
It is a genuinely useful test, and I use it. But it is routinely oversold, so here is what it does not do.
It does not test the baby. The cells biopsied come from the trophectoderm, the part of the embryo that becomes the placenta — not the inner cell mass that becomes the fetus. We are inferring the embryo's chromosomes from a neighbouring tissue.
It does not always represent the whole embryo. Some embryos are mosaic, meaning they contain both normal and abnormal cells. A biopsy of a few cells can land on either population.
It does not screen for inherited conditions. PGT-A counts chromosomes. It does not look for cystic fibrosis, sickle cell disease, or any other single-gene condition — that is a different test, PGT-M.
And it does not reliably improve your odds of a baby. This is the part that surprises people. A multicentre randomised trial published in Fertility and Sterility compared choosing embryos by PGT-A against choosing them by appearance alone in good-prognosis patients. Ongoing pregnancy rates were essentially the same — 50% with testing versus 46% without. A subgroup of women aged 35 to 40 did appear to benefit per transfer, but that advantage did not hold up when the analysis accounted for everyone who started treatment, including those who never reached transfer.
PGT-A is best understood as a tool for ordering and deselecting embryos — avoiding transfers that were never going to work, and shortening the road to a euploid one. It is not a tool that creates good embryos where there were none.
What one euploid embryo actually means for your chances
If you have a single euploid embryo, you have a meaningful chance of a live birth from it — but not a guarantee, and this is where I want to be careful with you.
A common thing patients are told is that once an embryo is euploid, age no longer matters. That is not what the evidence shows. A 2023 systematic review and meta-analysis in Fertility and Sterility looked precisely at this question and found that women under 35 still had higher ongoing pregnancy and live birth rates after transferring a euploid embryo than women 35 and over (odds ratio 1.29). The authors' conclusion was direct: rising maternal age is associated with declining success independent of whether the embryo is chromosomally normal.
In other words, chromosomes explain most of the age-related decline in fertility, but not all of it. Egg quality is broader than chromosome counting, and the uterus and the rest of the biology are part of the picture too.
The practical takeaway I give patients: one euploid embryo is a real chance and worth being hopeful about. It is not the same as a baby, and if your goal is more than one child, one euploid embryo is rarely the end of the conversation.
If you have more than one euploid embryo, the next question is usually which to transfer first — and that is where morphology comes in. My embryo grading chart explains how blastocyst grades are read and how they rank against one another.
How this predictor works, and where it stops
The tool below estimates your probability of producing at least one euploid embryo during a first IVF cycle, from two inputs: your age and your AMH level. AMH is a hormone produced by developing ovarian follicles and is the best single marker we have of ovarian reserve — roughly, how many eggs are available to be recruited. Age predicts the proportion likely to be euploid; AMH predicts how many you are likely to get. You need both to answer the question. If you want to see where your own result sits, I have plotted average AMH levels by age in a separate chart.
I am an REI, not a data scientist, so I built this with BlueLabel AI. The model is a stacked ensemble classifier trained on many thousands of real clinical IVF outcomes. On its own validation data it achieves an AUC of 0.84 — useful, clearly better than guessing, and well short of certainty for any individual person.
Three limits worth stating plainly:
- It works between ages 29 and 44 only. The data it learned from is concentrated in that band, and outside it the model's accuracy falls away sharply. I would rather give you nothing than give you a number I do not trust.
- It predicts embryos, not babies. The output is the chance of getting a euploid embryo — not the chance of a live birth, which additionally depends on the transfer, the uterus, and a good deal of luck.
- It uses two variables, and you are more than two variables. Diagnosis, prior response to stimulation, sperm factors, protocol, and the individual laboratory all move this number, and none of them are inputs here.
The numbers in the chart above are this model's own output. They are not published figures from a study, and I have labelled them that way deliberately — you can see the full detail, and the model's known quirks, alongside the data table.
Other free tools to try on the Lucky Egg
The Euploid Embryo Predictor is one of several free tools I have built and published on this site. If this one was useful, these may be too:
AMH levels by age chart
See average AMH levels by age and plot your own result against them — the companion piece to the AMH figure you just entered above.
Embryo grading chart
What blastocyst grades like 4AA and 5BB actually mean, with all 36 grades ranked — useful once you know how many euploid embryos you have and need to choose which to transfer first.
Egg freezing success calculator
Estimates how many mature eggs or embryos you are likely to get from a cycle, based on your age and ovarian reserve.
Frozen embryo transfer date calculator
Works out the likely timing of a frozen transfer cycle from your cycle type and embryo maturity, so you can see the key dates ahead.
IVF due date calculator
Calculates your due date from your transfer date and embryo age, which differs from the usual last-period arithmetic.
Beta hCG level calculator
Tells you what week of pregnancy a beta hCG result suggests and how it compares to typical ranges — especially useful in early IVF pregnancies.
This tool is for educational purposes only and is not a substitute for professional medical advice. It considers just two of the many individualised factors that drive whether you produce genetically normal embryos. Please do not use it as a substitute for the conversation you should have with your own fertility team, who know your history and can interpret these numbers in the context of everything else about you.