Puberty Blockers

Scott Arthur Excerpts

Tuesday 23rd June 2026 Commons Chamber

[Dr Johnson]

My hon. Friend raises a very good point, and I will come to the data linkage study shortly. What we do know from the Cass review is that the vast majority of children who went on to puberty blockers in adolescence went on to receive cross-sex hormones, which are known to have permanent effects.

One fact that is crucially important is that it is not possible for clinicians to confidently determine which children with gender incongruence will persist with the trans identity into adulthood, and which will not. How can the clinicians possibly know that they are not injecting potentially dangerous drugs into children whose incongruence will resolve itself? The answer is that they cannot. Will the Secretary of State tell us whether he is aware of new evidence allowing clinicians to work out confidently which children will persist with the trans identity at 11 and which will not? We need to think about the risk involved in the treatment, and whether it is worth the benefits that they will purportedly receive.

The trial researchers suggest that they will take a wide approach to looking at potential benefits, that they will look at quality of life and body satisfaction, and that there must be a reasonable prospect of benefit; but how can they know whether there is a reasonable prospect of benefit when they do not know whether or not the condition will persist? Some have suggested that giving puberty blockers will help the few adults who retain their trans identity into adulthood to pass as the opposite sex. Does the Secretary of State think that the long-term damage to many is worth it for the cosmetic benefit of a few? The Medicines for Human Use (Clinical Trials) Regulations 2004 specify that “anticipated benefits” must justify the risk. This is an ethical rather than a medical question. Does the Secretary of State think that the benefits justify the risk?

I regret that we have ended up discussing the details of a clinical trial in the Chamber—the reality is that things should be done impartially by scientists in most cases—but with this topic we have seen the quashing of open debate, which is why we have ended up where we are.

I will move on to the point made by my hon. Friend the Member for Farnham and Bordon (Gregory Stafford). Even if the Secretary of State thinks the principle of the trial is right, he must surely agree that it is unnecessary and unethically broad. For example, if someone was designing a trial to treat children with a specific form of cancer, the children who would be entered into the trial would have that specific form of cancer. We would not include children with any disease, because that would make the results unreliable in terms of benefit to the target group and children would be unnecessarily put at risk of receiving experimental drugs that they did not need.

The same applies to this trial. The Cass report tells us that many of the children in the proposed trial will get better on their own. The Secretary of State said yesterday that

“we are talking about a very small subset of a very small group.”—[Official Report, 22 June 2026; Vol. 788, c. 56.]

[Dr Scott Arthur (Edinburgh South West) (Lab)]

The hon. Lady knows that she is one of my favourite Tories—I think I have said that before. She has quoted Baroness Cass many times. Of course, Baroness Cass thinks this trial should go ahead, because the benefits outweigh the costs. Why is Baroness Cass wrong and the hon. Lady right?

[Dr Johnson]

Well, one of the things with doctors is that if you ask two doctors, you might get two different opinions. I completely respect Baroness Cass. She has been president of the Royal College of Paediatrics and Child Health, of which I am a member, and she has done great work on the report that we commissioned in the last Parliament. I know she is concerned that people may obtain these drugs illegally if they are not provided, but I do not share that concern. Personally, I think the important thing is whether the people obtaining such drugs legally are using them in a way that is safe, and I am not convinced that that is the case.

[Dr Arthur]

By giving way a second time, the hon. Lady shows why she is my favourite Tory. Does Baroness Cass not say that she has met young people who have been self-medicating with testosterone, which is irreversible? That is one of the problems that we are trying to address through this trial. It is about protecting young people so that they are not going down their own medical pathway, but are listening to medical advice and are well supported in a coherent framework.

--- Later in debate ---

[Sarah Owen]

I know that further details will be coming from the Secretary of State as to what a marker of success is, but I think we have to ask ourselves what a marker of success is for the individuals and families. For some, staying in their sex from birth may look like success. For others, that will not be the case. This is very much on the individual.

[Dr Arthur]

Will my hon. Friend give way on that point?

[Sarah Owen]

I will not; I am going to make some progress, as I have been duly told to do.

The treatment of premature sexual maturity, or precocious puberty, in children—this is for children—uses puberty blockers now. The professors reported to our Committee that puberty blockers are

“recognised as a reversible treatment.”

Professor Butler added that we know

“from follow-up studies with children who have received it for precocious puberty that there are no ill health effects in the long term nor are there any negative effects on fertility recovery.”

Professor Grossman pointed to a “huge amount of evidence” from Harvard University highlighting successful treatment and outcomes for girls prescribed puberty blockers for premature sexual maturity

“in terms of fertility and their subsequent life.”

--- Later in debate ---

[Richard Quigley]

I will not, I am afraid—I did warn you, although I do like the hon. Gentleman very much.

[Dr Arthur]

Not too much.

[Richard Quigley]

Not enough to give way.

If we cannot trust Dr Hilary Cass, the author of a report that the Conservative party itself has endorsed, when she says she is

“absolutely convinced that more children will be harmed if we don’t do the trial than if we do,”

who exactly are we prepared to trust? Do we follow the evidence, the clinicians and the science, or do we retreat into denial, burying our heads in the sand and pretending that trans people do not exist and have never existed? The process the Government have chosen to follow is not reckless; it is rigorous. The MHRA and King’s College London have undertaken detailed scientific scrutiny, and a revised protocol has been agreed that meets the highest regulatory and ethical standards. That is exactly what responsible, evidence-led policymaking looks like.

It is up to us to decide what kind of Parliament we want to be: one that confronts complex and sensitive issues with care, compassion and evidence, or one that turns away, leaving vulnerable young people to navigate these challenges alone and in the shadows. For me, the choice is clear: we owe it to those young people not to look away, not to inflame and not to exploit, but to act, guided by science, led by compassion and grounded in responsibility. I am once again proud to be part of a Government who are doing just that.

--- Later in debate ---

[Dr Scott Arthur (Edinburgh South West) (Lab)]

This has been an interesting debate so far and I am grateful to follow the hon. Member for Canterbury (Rosie Duffield), who has worked so much in this area. We should all acknowledge that this is not an easy issue.

The reason why I wanted to speak in the debate is that back when I was trying to get elected in 2024, I met the mother of a young trans woman. She told me about how her daughter really started to come to terms with who she was when she was entering puberty, but that led her to stop eating because she did not want to go into puberty. Her condition got so bad that she had to be taken to hospital, and she almost died. We should not view this as a lifestyle choice, and we should not think that doing nothing comes with no consequences. I know that not all cases are the same, but the reality is that doing nothing is not the answer. We do have to answer these questions.

I welcome the news this week that the Pathways trial is set to go ahead. Since the Government announced an indefinite pause on the prescription of puberty blockers last year, both young people and clinicians have been stuck in limbo. This uncertainty has helped no one—not the young people who are desperate for medical support, nor the researchers who need to gather data to fully understand the effects of these drugs. However, it is right that this renewed permission for a trial is based on clinical judgment, not political discourse. We should be led by science, not politics, where the health of our young people is concerned.

King’s College London and the MHRA have worked extensively to propose a safe and ethical trial, increasing safeguards since March and continuing dialogue with the Health Research Authority. I understand the concerns around the trial, and I think we all should. We all want to ensure the safety of the children involved, but it is time we find a way forward that balances the safety of the young people involved and the opportunity to enhance the care that we provide for children struggling with their gender identity. Far too often, that care is lacking.

Many Conservative Members have consistently called for the full implementation of the Cass review. Baroness Cass was quoted multiple times by the shadow Minister in her introduction to this debate, yet the Conservatives have called this debate to oppose the trial, despite it being one of Baroness Cass’s recommendations. Why are the Conservatives not willing to listen to Baroness Cass on that single issue?

In her original review in 2024, Baroness Cass made it clear that research into puberty blockers was necessary. Just this week, she has said that the trial to examine the risks and benefits of puberty blockers will reduce harm, not cause it. In fact, she goes further and tells us that the debate around the risks of puberty blockers has been exaggerated—we have seen some of that today, if we are all honest. She is absolutely right on this point.

[Tom Hayes (Bournemouth East) (Lab)]

The Conservative Government commissioned the Cass review. In their 2024 manifesto, the Conservatives committed to implement the review in full, which would include a trial. However, as my hon. Friend is saying, they now propose in this motion to stop the trial. Is that not proof that we actually need to have a trial? We need to take the party politics out of this matter, stop politicians from being the lead commentators and put it in the hands of the families and the clinicians.

[Dr Arthur]

Exactly. Baroness Cass is a respected expert in this field, and she made recommendations that were broadly accepted. We should be using science as a basis for decision making, not rejecting her findings purely on the basis of politics. Let me go back to what I said at the start: doing nothing will lead to our young people being harmed. That is an incredibly important point.

We cannot rely on debates in this place to decide how and when puberty blockers should be used. Rather, we should be relying on thorough scientific research, carried out in proper trial conditions and led by medical experts. We heard earlier the Health Secretary explaining some of the detail around protections for our young people. Baroness Cass is also clear that more children will be harmed by preventing the trial than by allowing one to go ahead. That is an incredibly important point.

Preventing a trial drives desperate children to look online or internationally for unregulated hormones or hormone suppressants. That leads young people to unsafe puberty blockers or to start taking hormones such as testosterone at a much earlier stage, which are irreversible once they start to take hold. We can prevent that by providing the properly regulated use of puberty blockers in the UK via this trial. The trial will provide understanding and allow clinicians to effectively guide Government on our next step. It is the right and necessary thing to do for the Government, clinicians and young people. We need to take better care of our young people, and we need to do that via a clinical trial.

Let me say again that doing nothing might seem like the easy thing to do, but it will come with consequences. I really hope that we hear more from Opposition Members about what they think the consequences of doing nothing will be for the health and wellbeing of our young people, because we have not heard that.

[Simon Hoare (North Dorset) (Con)]

Will the hon. Gentleman give way?

[Dr Arthur]

I will, because I know the hon. Gentleman is keen to speak.

[Simon Hoare]

My hon. Friend the Member for Reigate (Rebecca Paul) mentioned the recently published studies in Finland. Does the hon. Gentleman not think there is any merit in waiting to see what the Finnish tests and trials throw up? We could then see what we could learn from them, rather than replicating or duplicating them here. International science should surely be respected.

[Dr Arthur]

I welcome that fantastic point. Until I was unexpectedly elected, I was an academic, and what I learned was never to focus on a single study when doing research, because a single study is basically an anecdote. We have to look at the breadth of the research. If I may say so, we see exactly the same in the climate change debate—the broad spectrum of science supports the argument for climate change, but there are always one or two contrary views. Those views are welcome, but we do not base our view on just one study; we look at the breadth of the research.

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[Sir John Hayes (South Holland and The Deepings) (Con)]

The journey from childhood to adulthood is challenging for many, difficult for some, and tortuous for a few. Through that journey, the support of older people, who are often parents, loved ones, people who care, is critically important. For those who suffer from gender dysphoria, that journey is all the more challenging. Many people—perhaps all of us in this Chamber—will have struggled with the emerging sexuality that is part of the journey to adulthood, but most people who suffer from dysphoria cope with it as they go through puberty. Indeed, the evidence—and there has been much talk of evidence in this debate—shows that medical intervention in those cases would not only be unnecessary but profoundly damaging.

Yet at the Tavistock clinic, the horrors of which I first highlighted in 2019, thousands of children were prescribed life-altering drugs. Indeed, it is more shocking still: more than 70 children aged three and four were sent to that clinic, and 382 children aged six and under were referred. The Government are fond, now, of speaking about the Cass review commissioned by. the previous Government, but the review was not welcomed by the Minister and the trans lobby. When it was commissioned, it was regarded with horror by those who presumably now support this trial.

The Cass review found that doctors must be extremely cautious about giving trans drugs to under-18s—not 11, 12 or 13-year-olds, but people under 18. It found that doctors must be able to

“refer to the longer-term benefits and risks”

of treatment options; that young children should have therapy before they are allowed to socially transition; that many parents expressed concern about their child being socially transitioned and affirmed in their expressed gender without parental involvement; that too many decisions about changing gender have been rushed, with too little consideration given to whether children might regret their actions later in life; and that childhood trauma, neglect and abuse feature heavily in the cohort of patients seeking gender change.

As many as two thirds of those referred had suffered neglect or abuse, with high levels of parental mental illness, substance abuse and exposure to domestic violence. Those are the vulnerable children who went to the Tavistock clinic, which was closed after pressure from those who understood the horrors that took place there. When it was opened, of course—

[Dr Arthur]

Will the right hon. Gentleman give way?

[Sir John Hayes]

I will in a moment, when I have made an attack on the liberal bourgeoisie, which the hon. Gentleman might want to hear. When the Tavistock clinic was opened, it was seen as an emblem of progress by the liberal bourgeoisie. Now, of course, we know that it was the embodiment of wickedness. On that note, I give way to him.

[Dr Arthur]

I am part of the liberal working class. This debate is not about the Tavistock clinic. The right hon. Gentleman has just quoted Baroness Cass, but one thing he has not said is that she recommended that the clinical trial go ahead. She said recently that she supports the trial because she thinks there will be real benefits to it. Rather than talking about Tavistock, will he address what Baroness Cass, who he quotes extensively, thinks about this trial that we are debating?

[Sir John Hayes]

Baroness Cass certainly wanted to gather more evidence. The evidence we have shows the damage that puberty blockers can do. We know that the substantial science suggests that they affect bone maturation, cerebral capacity and, of course, fertility. It is certain that there is no compelling evidence that puberty blockers have a beneficial effect. That is why she sought more evidence, as she concluded that there was no compelling evidence that they have a beneficial effect.