Late last year New Yorkers noticed a series of strange advertisements on the subway. “Have your best baby,” one promised. “IQ is 50% genetic,” noted another. Predictably, they stirred controversy. Yet Kian Sadeghi of Nucleus, the embryo-screening startup behind them, was pleased. “This is a mass-market product. What’s a better way of showing that it’s a mass-market product than the subway?”
Nucleus is one of a growing number of Silicon Valley startups pushing the nascent technology. Noor Siddiqui of Orchid, a competitor, likes to say that “sex is for fun; embryo screening is for babies”. Herasight, another rival, began offering a screening service last year that allows parents to examine an embryo’s risk of various diseases, and also estimates of its height, intelligence and longevity—at a cost of up to $50,000. Nucleus adds hair and eye colour to the mix. The burgeoning industry aspires to reshape the way humans are made.
Not everyone is pleased. In many jurisdictions, including Britain, screening embryos for sex, let alone for polygenic conditions such as hypertension or physical traits such as height, is illegal. Many geneticists and doctors’ groups are sceptical that the technology works. Others say it is unethical. In America, where regulation is looser, religious conservatives and adherents of the “Make America Healthy Again” movement are vehemently opposed.
The startups’ visions may seem otherworldly. But change is coming fast. Cash is pouring into fertility research, leading to potentially rapid advances in genetic testing. Polygenic screening, particularly for common diseases, is popular among Americans, nearly three-quarters of whom say they would use it if they were already undergoing in-vitro fertilisation (IVF). A fight is brewing over the future of these technologies—and the businesses promoting them.
For the moment, only a tiny share of babies are born via IVF, as is necessary for embryo screening. In 2024, the most recent year for which figures are available, 100,000 American babies were created using the process, representing 2.8% of the total. David Sable, an investor and formerly a practising reproductive endocrinologist, says the global fertility market is commonly estimated to be worth just $25-30bn a year.
Yet Silicon Valley’s interest in fertility could expand access to IVF. Several years ago Peter Thiel and Elon Musk began to speak about low birth rates as a threat to America, and started putting money into fertility startups. They were joined by other investors. American venture-capital (VC) investments in fertility enterprises nearly doubled between 2019 and 2022, jumping from $254m to $496m, according to PitchBook, a data provider, even if they have since slowed a bit.
Many of these startups are focused on making IVF cheaper. At present, only 15 American states require the treatment to be included in insurers’ maternity benefits, meaning most Americans pay out of pocket. To reduce costs, a number of startups are selling fertility insurance and payment plans. Nader al-Salim of Gaia, one such firm, says its services save patients an average of $15,000 over the entire fertility process, largely by pooling risk.
Dr Sable reckons that if IVF does become much more widely available, the embryo-screening market could grow to $400-500bn annually. His estimate assumes the cost will fall to around $15,000 for the entire process; currently, just one cycle of IVF in America costs $15,000-20,000. Dr Sable reckons that prices will drop thanks to technological innovations which may increase success rates, allowing people to go through fewer cycles. Falling labour costs, as a result of automation and economies of scale, as well as greater standardisation should also help.
Some screening is already common among IVF patients. One example is PGT-A, which checks embryos have the right number of chromosomes, and which some studies claim lowers the miscarriage risk (many experts are sceptical). Certain clinics also offer PGT-M, which checks for disorders caused by a single gene, such as cystic fibrosis or Huntington’s.
Now startups are adding a third screen: PGT-P, which scores embryos for conditions and traits determined by multiple genes, potentially ranging from certain cancers to eye colour and IQ. Demand for such tests could be substantial. A survey published in 2023 in Science found that 43% of all IVF participants would use polygenic screening to increase their child’s chance of getting into an elite university, provided it were safe and free. A third said the same for genetic editing.
Consider Arthur Zey, a software engineer, and his husband Chase Popp, a teacher. Mr Zey says he has always been a “tech nerd” and wanted to apply his skills to the process of having a child. “Most of my professional career I’ve been a product manager in tech, and so in some ways this is just like another product to manage,” he says. Earlier this year the couple had a son using an embryo selected from a group of six on the basis of the results of polygenic screening provided by Herasight. That allowed them to see risk scores for monogenic diseases and more than a dozen polygenic diseases. The startup also gave them predicted ranges for IQ and height.
Messrs Zey and Popp say they hoped to maximise their son’s lifespan, rather than his height or IQ. Yet Mr Zey knows there are advantages to being tall and smart. “All I could do is look at the results for my six embryos and say: ‘Okay, it kind of seems like this one is better.’”
The burden of perfection
For now, Messrs Zey and Popp are unusual. Commercial PGT-P screening is a niche industry. Startups like Herasight cater to a small population of typically very rich people, mostly in America. Even so, that has not stopped them from drawing plenty of criticism.
Some concerns the underlying science. Polygenic risk scores are based on genome-wide association studies (GWAS), which use data from large populations to try to discern associations between genetic variants and specific conditions and traits. Companies that offer screening claim that comparing embryos’ genomes to risk scores derived from these databases, sometimes with adjustments based on ancestry and family history, allows them to come up with individual assessments.
That is disputed, however. Although selecting on the basis of polygenic risk scores works across many offspring, as in animal breeding, it is less sure to have the desired result for a single child, notes Kevin Mitchell of Trinity College Dublin. For example, an embryo’s genome may have a single rare variant that has a large effect on its likelihood of developing a certain condition, but which would be unlikely to surface in population-level correlations.
Herasight attempts to deal with this issue by validating its risk scores using sibling data from GWAS datasets to ensure its models retain predictive value within a single family. It claims that, if it tests ten embryos for a couple where both parents have type-2 diabetes, it can reduce their child’s absolute risk of developing the condition by 12-20 percentage points, from a baseline of 40-60%. Herasight has been critical of competitors, particularly Nucleus, for not providing more detailed public information about their methodology. (Nucleus, for its part, says it is working constantly to ensure its scores are accurate.)
Some also argue that the magnitude of the benefits from embryo screening are overstated. If parents picked from ten viable embryos, the median boost to their child’s height would be 2.9cm, according to a paper in Cell in 2019, based on technology at the time. If they selected for IQ, the gain would be three points—unlikely to be life-changing. Moreover, for those picking among fewer than five embryos, the expected gains drop precipitously. Although the average number of viable embryos depends on the patient’s age, in many cases it is closer to two or three from each IVF cycle. Dagan Wells of the University of Oxford adds that, for many conditions, genes are less important than environmental factors such as diet.
Selecting against some traits could also have unintended consequences. Genetic material can have different effects in different parts of the body, a phenomenon called pleiotropy. If parents select an embryo intending to lower their child’s risk of a certain disease, they may be neglecting or exacerbating problems for which providers do not (or cannot) offer a score.
Yet many of the technical issues, not least the lack of training data among certain populations, should improve with time. The Cell paper estimated that increasing the sample size of the underlying databases could double the median gain in IQ points from polygenic scoring. Or consider the effects of rare genetic variants. As databases grow, artificial-intelligence models may be better able to account for the effects of individual variants. With pleiotropy, some studies suggest that most genetic correlations between pairs of polygenic diseases are either positive—meaning cutting the chance of one decreases the chance of others—or insignificant. At present, the technology is “kind of a promissory note”, says Trinity’s Dr Mitchell. “They say, ‘Trust us, this is a bit shit right now, but it’ll be good soon’.”
If technological problems are resolved, ethical ones will only grow. Disability-rights groups are already wary of PGT-M, worrying it suggests lives with certain genetic conditions are not worth living. The rise in use of PGT-P widens that debate to many more traits. Then there are opponents who are concerned that screening startups are promoting a friendlier version of eugenics. Some worry that embryo editing—on which America has applied a de-facto ban since 2016—could come next.
Industry insiders reject the fretting, sometimes bluntly. Risk scores may not be perfect, but they are “best in class”, says Delian Asparouhov of Founders Fund, a VC firm co-founded by Mr Thiel, which has invested in various fertility startups. “What I hate about some of the traditional health-care industry and genetic counsellors is they’re like, ‘You need to have a Harvard clinical-grade license’” to interpret genetic data. “Fuck that,” he continues. “I just want whatever the best statistical models are. I don’t need a PhD to read this stuff.” (Herasight, Nucleus and Orchid all have genetic counsellors to walk clients through their results.) As for ethics, Mr Asparouhov argues that all parents-to-be engage in a form of genetic selection when they choose a partner. “If this is eugenics, then so is Hinge,” he argues.
Most of the companies offering PGT-P are more circumspect. They say their customers are mainly looking for ways to ensure their children are healthy, rather than to create “super-babies”. Yet their decision to offer scores for intelligence and aesthetic traits suggests they recognise there is a market for the latter.
Arguments over the future of a small cohort of startups may seem like a niche concern. But if IVF gets cheaper and genetic data more abundant, as looks likely, the business of embryo screening will only grow—along with the ferocity of the debate. The nearly 50-year history of the fertility industry is full of technologies that were once contentious, including IVF. Startups like Nucleus, Orchid and Herasight are, in that sense at least, nothing new.
