Designer Babies, IVF and Embryo Screening: Ethics for Medicine Interviews

Designer babies ethics is mostly an argument about something that does not yet exist. UK law lets IVF embryos be screened for serious inherited conditions, and for a tissue match to save a sick sibling, while choosing intelligence or appearance stays unlawful. Medicine interviews use it to see whether you argue from the law or from a headline.

I'm Dr Akash Gandhi, an NHS GP who has been preparing applicants at TheUKCATPeople since 2012. Designer babies and embryo screening come up every single interview season, usually because a candidate has read a headline rather than the law behind it. Our guide to answering medical ethics interview questions gives you the structure.

What is a designer baby?

A designer baby means a child whose characteristics were chosen in advance, and no child like that exists anywhere. What a clinic can actually do is test the embryos a couple has already created and then choose between them.

• Selection is not design: a clinic can rank the embryos in front of it, though it has no way to invent another one. Where neither parent carries a variant, there is nothing for a test to find.
• Complex traits do not work that way: height and intelligence involve thousands of variants of tiny effect, and then everything that happens after birth on top of that.
• Trait screening is unlawful here: testing embryos against risk scores is called PGT-P, and the regulator rules it out as unlawful and unsupported by evidence.
• Editing is a different argument: rewriting DNA rather than selecting embryos has its own law, and belongs to the gene editing debate.

Are designer babies legal in the UK?

No, and the list of what's permitted is narrower than most people assume. Embryos may be tested for serious conditions the regulator has approved, for chromosome rearrangements, and for a tissue match to help a sick sibling, which leaves height, intelligence and appearance well outside it.

When I run mock interviews, the answer that comes unstuck is almost always the one describing parents ordering features from a list.

Key Takeaway: Selection can only choose between embryos two people have already made, so a designer baby describes a technology that nobody actually has.

How does embryo screening work, and what does UK law allow?

Embryo screening is only possible through IVF, and here it's licensed condition by condition by the Human Fertilisation and Embryology Authority, the HFEA. A few cells are taken from each embryo and tested, and one unaffected embryo is transferred later on.

The table below is most of what you need.

Over 2,000 conditions are approved for PGT-M, and a clinic wanting anything else must apply to the HFEA. The criterion is a significant risk of a serious condition, so what the UK maintains is a list of permitted conditions rather than a list of banned traits.

Access is uneven: only 28% of UK IVF cycles were NHS funded in 2024, which is the postcode lottery argument and a question of justice.

Key Takeaway: The UK approves conditions rather than banning traits, and that inversion is the single most useful thing to know here.

What is a saviour sibling, and are they legal in the UK?

A saviour sibling is a child conceived by IVF and selected because their tissue matches a seriously ill brother or sister, so that marrow or cord blood can be donated. It's legal here for serious blood disorders where no other matched donor exists.

The case: the Hashmis. Their son Zain had beta thalassaemia, inherited from both parents, so any future pregnancy carried the same risk. In December 2001 the HFEA allowed tissue typing alongside the screening those embryos already needed.

The case: the Whitakers. Their son Charlie had Diamond Blackfan anaemia, which he hadn't inherited, so their embryos were all perfectly healthy. In August 2002 the HFEA refused, because a tissue match would have been the sole reason for testing them.

That line lasted barely two years. In July 2004 the HFEA allowed tissue typing on its own, and the House of Lords confirmed in April 2005 that it had the power to license it.

Is a saviour sibling only wanted as a donor?

No, and a child wanted both for their own sake and to help a sibling seems to me no worse off than one wanted for a single reason. The harder point is that a family in that position is under enormous pressure, and beneficence towards the sick child can crowd out everything else, as Charlie Gard showed.

• Consent comes later: once old enough, the child can be asked whether to donate again, which is consent and Gillick competence territory.
• Cord blood is not bone marrow: collecting cord blood is harmless, whereas a marrow harvest from a child too young to agree raises a real non-maleficence problem.

Key Takeaway: The regulator drew its line at whether the embryos needed testing anyway, and then moved that line within two years.

What is PGT-A, and why is it controversial?

PGT-A counts an embryo's chromosomes, and it's controversial because it's one of the most widely sold optional extras in UK fertility treatment while the evidence behind it remains poor.

The HFEA rates add-ons on a traffic light system, where red means a safety concern or a possible drop in effectiveness. PGT-A is rated red for improving the chance of having a baby in most patients, and grey, meaning insufficient evidence, in older patients.

• It removes options rather than adding them: PGT-A acts as a filter that cuts the number of embryos available and can lengthen the time to conception, though it's rated green for reducing miscarriage.
• An abnormal result is not always right: an embryo can be a patchwork of normal and abnormal cells, so a biopsy of a few outer cells can lead to a perfectly viable embryo being discarded.

In my GP clinics, people come back from a private cycle holding a price list and wanting to know which of the extras were worth paying for. Telling them that the regulator publishes exactly that judgement, free of charge, is often the most useful thing I say all week.

Key Takeaway: Naming one add-on that is popular and unproven shows you understand evidence-based medicine rather than just the phrase.

Can you choose your baby’s sex in the UK?

No, at least where the reason is social or family balancing. Sex may only be selected where it relates to the health of the resulting child, which in practice means avoiding a serious condition affecting one sex, such as Duchenne muscular dystrophy or haemophilia.

• For allowing it: reproductive autonomy is a strong principle, and no third party is obviously harmed when a family with two sons want a daughter.
• Against allowing it: where son preference is strong, permitting choice has skewed sex ratios across whole populations. Discarding a healthy embryo because of its sex also sits awkwardly alongside the claim that sex is simply a characteristic rather than a defect.
• What the public said: when the HFEA reported on its consultation in November 2003, 80% of the 600 respondents opposed sex selection for non-medical reasons.

Key Takeaway: The UK ban rests on a judgement that the harms of sex selection fall on a whole population while the benefits sit with one family.

Is embryo screening a form of eugenics?

In the historical sense no, because the state directs none of it and no one is being forced into anything. The comparison still deserves a proper answer, because part of the objection survives the obvious reply.

The history is British. The word eugenics was coined by Francis Galton in 1883, and the Eugenics Education Society was founded in London in 1907. Parliament stopped short of a compulsory sterilisation law, whereas Germany passed one from 1933, and that is largely what discredited the movement here.

• Why it is not eugenics: the state decided, individuals were coerced, and the goal was improving a population rather than helping a family, and a couple choosing to avoid passing on Huntington’s disease falls outside every one of those.
• Why part of the objection survives: thousands of private, well-meant decisions can still change who gets born, and no individual chose that aggregate. The state is not neutral either: it licenses the clinics and approves the conditions.

Key Takeaway: The voluntary answer is right but incomplete, because a pattern nobody chose can still emerge from choices everybody made freely.

What do disability rights campaigners say about embryo screening?

They argue that when a society routinely screens out a condition, people living with that condition can reasonably hear something about whether they were wanted. It is a serious argument, worth stating in its strongest form.

When the Nuffield Council on Bioethics examined prenatal testing in 2017 it spoke to people living with Down’s syndrome and other genetic conditions. Its recommendations were restrictive: no testing for less significant conditions, carrier status, adult-onset conditions or non-medical features.

The case: in 2008, while Parliament debated what became the current law, the deaf couple Tomato Lichy and Paula Garfield objected to a clause preventing them from choosing a deaf embryo. They treat deafness as a culture and a language rather than a defect, as do some people with achondroplasia.

UK law gives them a flat no: an embryo known to carry a serious condition must not be preferred to one that is not. Selecting against deafness is allowed, selecting for it is not, and a regulator rather than the parents decides what counts as serious. The same tension runs through the abortion debate.

Key Takeaway: Screening against a condition and screening for one are legally opposite in the UK, and saying why shows you have thought about this properly.

How can I talk about embryo screening in my medicine interview?

Define the term first, then move to the two live questions: who decides what counts as a serious condition, and what happens when private choices add up. You are not expected to know the statute.

A structure that works in the room:

1. Define it, in one sentence: what selection can and cannot do.
2. Name the law: the HFEA approves specific conditions, tissue typing is allowed for serious blood disorders, and trait screening is not.
3. Give both sides: reproductive autonomy against the message screening sends and the aggregate effect.
4. Land a position, without hedging every clause.
5. Say what would change it, such as screening drifting towards traits.

What interviewers are testing here:

• Ethical reasoning, not statute: a date slightly wrong matters far less than having no structure.
• Whether you can argue the side you disagree with: stating the disability rights objection properly is part of understanding it.
• Whether you remember the families: these are decisions about a couple who carry cystic fibrosis, or a child with thalassaemia, not a thought experiment.

If you have volunteered with disabled people, or cared for a relative with a long-term condition, say what that taught you about how differently people describe the same condition. Our medicine interview tutoring runs mock MMI and panel stations with feedback.

Key Takeaway: Define, name the law, give both sides, land a position, then say what would change it.

What interview questions could come up on this?

You are unlikely to be asked any of these word for word, and you do not need a prepared answer to each one. Use them to check your understanding: if you could speak for a minute on most of them, you know this topic well enough for whatever the interviewer actually asks.

Questions to get you thinking

1. What do you understand by designer babies, and are they possible?
2. What is a saviour sibling, and is it ethical to create one?
3. Should people be able to choose the sex of their child?
4. Is embryo screening a form of eugenics?
5. A friend says clinics can now select embryos for intelligence. What would you say?
6. On work experience, a woman asks whether the extra genetic test she has been offered is worth paying for. How do you respond?

Harder questions to stretch you

1. Where would you draw the line between a serious condition and a trait?
2. A deaf couple want to choose a deaf embryo. On what grounds would you refuse, and are those grounds consistent?
3. Who should decide which conditions can be screened for: parents, doctors, a regulator or Parliament?
4. If a test is popular with patients but unsupported by evidence, should clinics sell it?

Model answer: "Is embryo screening a form of eugenics?"

No, not in the way the word is normally used, but the comparison is doing useful work and I would not dismiss it.

Historical eugenics rested on the state deciding, on people being coerced, and on the aim of improving a population rather than helping a family. Britain went a long way down that road, because the word was coined here in 1883 and Parliament debated sterilisation more than once.

A couple who both carry cystic fibrosis, choosing an embryo that is free of it, falls outside every one of those features.

What survives is the aggregate effect. If enough families make the same private decision, the number of people born with that condition falls, and yet nobody chose that outcome as a policy. The state sits inside this too, because it licenses the clinics and approves the conditions.

I would also be careful how I talk about the conditions themselves. People living with a condition can reasonably hear a message in this, and a judgement about a condition settles nothing about a person.

What would change my view is drift. The UK approves specific serious conditions and does not allow embryos to be tested against risk scores for traits. If that moved, or if declining a test became something you were judged for, I would be much more uneasy.

Why this answer works:

• It defines the term before using it: naming what made eugenics eugenics lets the comparison be tested rather than asserted.
• It concedes the strongest counter-argument: giving the aggregate objection away early is more persuasive than defending against it, and it is careful about who might be listening.
• It says what would change its mind: naming drift turns a position into reasoning.

More questions sit in our medical school interview questions guide, and the wider set in our medicine interview hot topics guide.

Key Takeaway: Practise this out loud against a clock, because the eugenics question rewards a definition in the first fifteen seconds.

The one line to take into the room

Embryo screening chooses between embryos that already exist, which is precisely why it can design nobody. The live arguments are about who decides what counts as serious, and about what happens when a great many private choices add up. For the framework, read our guide to the four pillars of medical ethics.

Key Takeaway: Say what selection can and cannot do first, then name the two live arguments, and everything else has somewhere to attach itself.