Photo by Julia Taubitz on Unsplash
Published on November 28, 2025
by Sarah Ditum
Original: The Times – We’ll learn nothing from puberty blockers trial
Dr Hilary Cass had little option but to include this study but by its nature it will only reaffirm what volunteers already believe
For decades, when it came to the medical treatment of children who were unhappy with their birth sex, the trans activists had one refrain: drugs that halt puberty (generally known as “blockers”) were proven to be safe, reversible and life-saving. Thanks to Dr Hilary Cass’s landmark review into gender identity services for children, published last year, we now know that none of that was true.
The implications of that were truly shocking. We simply don’t know whether the children who received blockers were being helped or harmed.
The evidence base for treating children with these drugs was, on sober inspection, so slight as to be basically non-existent. The gold standard in medicine is the randomised controlled trial (RCT), in which one group receives the treatment being tested, while a control group receives either a different treatment or none. But, as Cass noted, barely any RCTs had been conducted on hormone treatments for adolescents.
The implications of that were truly shocking. We simply don’t know whether the children who received blockers were being helped or harmed. Many of those working in the specialism had a quasi-religious faith that this was the right thing to do, and a consequently lax attitude to research and follow-up. Why bother collecting and publishing data if you’re already convinced that you’re on the true path?
The immediate consequence of the Cass Review was that the government announced an indefinite ban on puberty blockers for under-18s. This was a cause for celebration among anyone who had grown alarmed about the treatment of gender-distressed young people, a vulnerable group with a complicated set of psychological issues that were rarely resolved by changing their bodies.
But among Cass’s recommendations there was one that caused the gender critical contingent some concern: she called for an RCT of hormonal treatments for children with gender dysphoria, opening up the reintroduction of puberty blockers in the NHS under the guise of research. Now, the structure of that study (based at King’s College London and called the Pathways Trial) has been revealed. And nobody is happy.
The whole premise is flawed. Gender dysphoria is an issue, ‘trans’ is the wrong solution.
Pathways is actually three trials in one. The first will recruit 226 adolescents with gender dysphoria: half will receive blockers straight away, and half will receive them after a 12-month delay. Alongside that, 300 adolescents with gender dysphoria will be assigned to a group called Horizon Intensive: they will not be prescribed blockers and will be observed for comparison. Finally, a study called Connect will compare brain development in the three cohorts.
Puberty blockers are difficult to study — you can’t do a double-blind placebo test, for example, because a teenager can obviously figure out whether they’re going through puberty or not — and this is a fairly elegant solution to some of the problems. In theory, Pathways could fill some of the gaps in our knowledge. In practice, the trans activist side is furious because this study means blockers will only be available to the 226 children enrolled in Pathways — “heartless and discriminatory”, says the trans charity Mermaids, which advocates early and extensive medical interventions. Meanwhile, some gender critical campaigners think it shouldn’t be happening at all.
They might well be right. Cass probably had no choice other than to include the recommendation for this study: without it, her review could have been dismissed as anti-trans propaganda (and even with it, many have tried to smear her with that claim). But the ethical issues and confounding factors involved are beyond even the most subtle research protocol.
One issue is that the children who volunteer for the trial will by definition already believe that medication is the answer to the “problem” of their maturing bodies, as will their parents and medical providers. When their puberty is paused, they will experience that as a positive outcome. All it will mean, though, is that people tend to be happy when they get what they want, and that is hardly a basis for medicine.
Blockers are “the beginning of the physical ‘cure’ for a psychosocial problem”, says Dr Melissa Midgen, a child and adolescent psychotherapist who formerly worked at the Tavistock Gids clinic, and has long expressed concerns about the use of hormone treatments in young people. “The whole premise is flawed. Gender dysphoria is an issue, ‘trans’ is the wrong solution.”
However well intentioned this study is, it is asking the wrong questions, and that means it can only deliver the wrong answers.
She points out that we already know from the Tavistock’s own limited data that, once children are put on to blockers, they almost always continue to cross-sex hormones. In other words, while blockers might be reversible in a very limited sense (though even then, some side-effects to bone density and brain development could be permanent), in practice they “fix” the child in their trans identity.
That’s especially serious because transition is far from a neutral outcome. For example, adolescents enrolled in Pathways will receive fertility counselling, because disrupting the natural process of puberty has obvious consequences for fertility and sexual function: the children who have these treatments have a high risk of growing up to be adults who can never conceive naturally or fully enjoy sex.
In medical jargon that’s called “reproductive toxicity” and for most medications it would be serious cause for concern — it might even stop a drug from getting beyond the animal trial stage. But when we’re talking about boys and girls who hate their bodies, for some reason different standards apply.
The children who participate in Pathways are being asked to pay a high price for the sake of knowledge that will almost unavoidably be of poor quality. We may not know much about blockers but we should know that normal puberty is not a disease. No child is born in the wrong body. However well intentioned this study is, it is asking the wrong questions, and that means it can only deliver the wrong answers.