Research, explanations, and practical guidance for families considering embryo screening.
Featured article
Conditions & traits
If you're going through IVF and are testing your embryos for the risk of developing complex diseases, you may wonder whether it’s also possible to test for intelligence. The answer is yes: intelligence is moderately to highly heritable (Plomin & Deary, 2015), and Herasight has developed a powerful polygenic predictor of intelligence (Wolfram et al., 2026).
Evidence about inherited disease risk, cognitive ability, and developmental traits.
Conditions & traits
Parents who ask us about schizophrenia screening have usually been thinking about it for a long time. They’ve watched a father lose a job, a sister stop calling, a son move back home in his twenties. They know what it look like living with the disease, because they've already been there when it happened to someone they love.
Conditions & traits
Rheumatoid arthritis is a parent's morning stiffness, the rotation of DMARDs on the kitchen counter, the two-month rhythm of rheumatology appointments, and the slow recalibration of what a good day looks like. Yes, RA runs in families, but not the way a single-gene disease does.
Conditions & traits
When a parent has a heart attack in their fifties, or a sibling gets put on a statin in their forties, pretty much everyone in the family starts doing the quiet math about their kids. The honest answer to what they're asking is yes: a meaningful share of that risk is inherited. Twin studies put the heritability of coronary artery disease somewhere between 40% and 60%, with one Swedish registry following 20,966 twins for 36 years and landing at 0.57 for men and 0.38 for women.
Conditions & traits
Most families who worry about hereditary breast cancer are thinking about one thing: BRCA. That's understandable. BRCA is the name that shows up in genetic testing ads, in conversations at the oncologist's office, and in the news. But BRCA mutations account for roughly 3% of all breast cancer cases. The other 97% involve a completely different kind of genetic risk, one most families have never heard of.
Conditions & traits
The conversation sits behind almost every search for "is Type 1 diabetes hereditary." A clinician said the words "higher risk." No baseline, no scale, no sense of whether "higher" means a couple of percentage points or a near-certainty. The math is doable. It just didn't get done in the room. For a future parent with T1D in the picture (yours, your partner's, or a sibling's), the honest answer is short, and most pages give it badly. Type 1 diabetes is one of the most heritable common diseases we know of. Most children of T1D parents never develop the disease. Both halves of that sentence are true at the same time, and the gap between them is exactly where a family-planning decision lives.
Conditions & traits
If you or your partner has a family history of bipolar disorder, and you're thinking about IVF, you may wonder whether there’s a test that can reveal the risk of bipolar for your embryos. The answer is yes. Although bipolar is caused by many genes, we sum up the risk of each of those genetic variants to create an overall score that parents can use to prioritize which embryo to implant.
Conditions & traits
If you've watched a parent start forgetting names, you've probably asked yourself the question most doctors won't give you a straight answer to: Could I pass this on to my children? Yes. You very likely could. And the degree to which that's true is bigger than most people realize.
Conditions & traits
If you or your partner has ADHD, or it runs in your family, chances are you've thought about whether your child might have it too. Maybe you've been told it's about parenting, or diet, or screen time, or that kids grow out of it. Most of the conventional advice for parents in your situation focuses on environmental factors, because those were the only things anyone could change.
Conditions & traits
If you're a parent with type 2 diabetes, or you have an immediate family member with the condition, chances are you've occasionally thought about what you might be able to do to prevent your child from getting the disease. Typical advice given for parents in your situation is about lifestyle: what foods to feed your children, how to keep them physically active, how to manage their weight, and even advice about breastfeeding.
Plain-language guides to testing types, timelines, cost, and fertility decisions.
IVF & PGT guides
The cost of egg freezing usually arrives as a single figure on a clinic page, weeks before the first consultation. It's a five-figure number large enough to change a year's savings plan, and a careful reader can see it against her bank balance long before she knows what's actually in it.
IVF & PGT guides
If you just got PGT results back, you probably want a straight answer: can I trust these numbers? It depends which numbers you're looking at. If your embryo came back euploid or aneuploid, yes. Those calls are reliable. But if you got a mosaic result, the honest answer is that the classification itself is only right about half the time.
IVF & PGT guides
If your clinic has mentioned PGT, chances are they presented it as one thing: PGT-A, a chromosome count. What they probably didn't tell you is that there are two other forms of preimplantation genetic testing, and they answer completely different questions about your embryos. The difference matters more than most families realize.
IVF & PGT guides
PGT is a set of genetic tests run on embryos before transfer. Depending on which type, it can tell you whether an embryo has the right number of chromosomes, whether it carries a specific inherited mutation, or what its overall risk looks like for common conditions like heart disease, Alzheimer's, and schizophrenia.
IVF & PGT guides
Polygenic embryo screening is a type of genetic screening available to parents going through IVF that estimates each embryo's predisposition toward common diseases. It can be used to reduce a future child's risk of type 2 diabetes, breast cancer, Alzheimer's, heart disease, and more. It's a significantly more comprehensive version of the genetic testing that's been available for decades, which could only screen for conditions caused by a single gene, like cystic fibrosis.
IVF & PGT guides
If you've just gotten a quote for preimplantation genetic testing and called your insurance company, you probably got one of two answers: "not covered" or "we'll need to look into that." Neither tells you much.
IVF & PGT guides
Most IVF patients hear "your embryos were tested" and assume that covers everything. It almost never does. Embryo screening isn't one test. It's three, and each one answers a fundamentally different genetic question. One counts chromosomes. One looks for specific inherited mutations like cystic fibrosis. And the third measures the combined effect of hundreds of genetic variants on common disease risk.
IVF & PGT guides
PGT-A is a genetic test available to parents going through IVF that checks whether each embryo has the right number of chromosomes before transfer. A few cells are biopsied from the outer layer of a Day 5 or Day 6 blastocyst, the lab counts chromosomes, and embryos with the correct number (euploid) get prioritized. It's the most common add-on in embryo screening, and nearly half of all IVF cycles in the US now include it.
IVF & PGT guides
Most IVF families learn about embryo screening backwards. Your clinic mentions PGT-A. Maybe a counselor brings up PGT-M. And if you've done enough late-night reading, you might've stumbled across PGT-P. But nobody sits you down and shows you how all of these fit together, what each one actually tests for, or what falls through the cracks when you only do one.
IVF & PGT guides
You've had your embryos biopsied, and now you're getting three different answers to what should be a simple question. One clinic says one to two weeks. Another says six to eight. Someone who did PGT-P says it took even longer.
IVF & PGT guides
"How much does PGT cost?" is the wrong question. Not because cost doesn't matter, but because the number your clinic quotes you is hiding most of the actual expense, and the number you should really care about isn't even on the bill.
IVF & PGT guides
If you're going through IVF and your clinic hands you a report with risk percentages for a dozen conditions across five embryos, chances are you're going to stare at it and feel completely lost. A genetic counselor is the person who turns those numbers into a decision you actually feel good about. They look at your family history, explain what the scores mean for your specific situation, and help you weigh trade-offs that no PDF can walk you through on its own.
IVF & PGT guides
Preimplantation Genetic Testing for polygenic traits (PGT-P) allows parents going through IVF to measure the likelihood that an embryo will develop a particular disease. In addition to giving parents information about disease risk, PGT-P can also predict traits ranging from height to intelligence.
How prediction, ancestry calibration, within-family validation, and study design work.
Evidence & methods
If you're not of European descent and you've looked into polygenic screening, you've probably hit the same wall: most genetic risk scores were built on data from white people, and their accuracy drops (sometimes by more than half) when applied to anyone else. That's a real problem. Cross-ancestry accuracy, meaning how well genetic predictions perform across different ancestral backgrounds, has been the field's biggest equity failure. A 2019 study by Martin et al. found that polygenic risk scores were several times more accurate in Europeans than in anyone else, with accuracy losses exceeding 75% in African populations. For years, it looked like polygenic screening might be fundamentally limited to one slice of humanity.
Evidence & methods
If you're a prospective parent researching polygenic embryo screening, you've almost certainly hit this claim: a 2019 study in Cell found that screening embryos for height and IQ would gain "only about 2.5 IQ points." It shows up in Science magazine, in policy discussions, and in pretty much every article arguing that embryo screening has "limited utility." Most of that criticism is aimed at cognitive screening specifically. There are two problems with how the study gets used.
Evidence & methods
If you've looked into polygenic embryo screening, you've probably come across accuracy numbers. A score "explains 20% of disease variance." An AUC of 0.75. Those numbers come from real published research, and they look solid.
Evidence & methods
If you're over 35 and going through IVF, chances are your RE has shown you the chart. You know the one. Success rates drop off a cliff around your age and approach zero by the early forties. It's one of the first things they show you, and it's hard to unsee.
Practical choices, comparisons, critiques, and ethical questions around embryo screening.
Decisions & perspectives
The word "eugenics" is occasionally associated with embryo screening. But the word “eugenics” is ambiguous between voluntarily selecting children with various genetic advantages, states intervening to shape the traits of populations, and states engaging in programs that are morally objectionable, such as mass murder in the name of eugenics.
Decisions & perspectives
Christopher Cox's New York Magazine piece raises the right worry about embryo screening: that some companies focus more on marketing than on improving their science. Moreover, as he argues, when some companies focus on relative risk reduction, rather than quantifying the absolute lifetime risk to an embryo of developing a disease, they are doing their customers a disservice.
Decisions & perspectives
Imagine you went through IVF and had five healthy embryos. Now suppose there are only two embryo screening companies. How would you decide which one to use?
Decisions & perspectives
If you're a reproductive endocrinologist or genetic counselor, you've probably settled on some version of this: polygenic embryo screening is interesting, but not ready. Professional societies urge caution. The evidence base is still developing. Better to wait.
Decisions & perspectives
You asked your fertility doctor about polygenic embryo screening, and they told you it's not ready. Maybe they said the science isn't there yet. Maybe they said professional societies recommend against it. You left the appointment feeling like the question was settled.
Decisions & perspectives
Every embryo screening company will tell you their test is worth it. Few will tell you when it isn't. The value of polygenic screening depends on your specific situation: embryo count, family medical history, and what you're hoping to learn. For some families, screening reveals meaningful risk differences between embryos. For others, it adds cost without changing the decision.