Puberty Blockers Clinical Trial

Debate between Tonia Antoniazzi and Jamie Stone

Monday 23rd March 2026 Westminster Hall

[Jamie Stone (Caithness, Sutherland and Easter Ross) (LD)]

I beg to move,

That this House has considered e-petition 751839 relating to the clinical trial into puberty blockers.

It is always a pleasure to speak under your chairmanship, Mr Mundell. I sincerely thank everyone I met in preparation for this debate: the legal and medical professionals who shared their expertise and the individuals with deeply personal, lived experience on both sides of this discussion. It goes without saying that this is a complex topic. I am grateful for the time and care that people have taken to help inform this debate.

I also thank the petition’s creator, James Esses, and petition supporter and campaigner Keira Bell. I had the pleasure of meeting them ahead of this debate, and they are watching today. Their petition asks that the clinical trial for the use of puberty blockers be cancelled. They believe that medical intervention in this area is dangerous, poorly evidenced and ethically questionable. They have asked Parliament to ensure that children are protected from potential harm.

I want to make it crystal clear that this debate is not about trans rights or whether people who identify as transgender have the right to exist and live free from discrimination. This discussion focuses on a clinical and ethical issue: whether puberty blockers should be prescribed to children experiencing gender dysphoria, and specifically whether a new NHS-backed clinical trial into their use should proceed.

Puberty blockers are medicines that suppress the production of sex hormones. They press pause on puberty, delaying changes like periods, breast development, voice changes and facial hair growth. Historically, they have been prescribed to children who enter puberty unusually early and, in some cases, for the treatment of cancers or endometriosis. Importantly, they are distinct from gender affirmation or cross-sex hormones. Blockers temporarily pause development, while cross-sex hormones actively induce the physical changes of the opposite sex and are generally irreversible.

The petition raises two main areas of concern: the possible long-term medical side effects of puberty blockers, and whether meaningful consent can ever be obtained from a child or adolescent.

[Tonia Antoniazzi (Gower) (Lab)]

The hon. Gentleman is making a very good start to his speech. I appreciate that this is very contentious, but I am concerned about the manner in which young people—children—are asked questions. The KIDSCREEN-10 index is a primary outcome measure for the PATHWAYS trial, and when I look at the questions, I wonder how my son would have answered them aged 11. One of them asks:

“Have your parent(s) treated you fairly?”

The truth is that any child at that age would probably say, “No.” Does the hon. Gentleman share my concern that these questions are not fit for purpose?

[Jamie Stone]

I thank the hon. Member for her intervention, but she will understand that it is my job as Chairman of the Petitions Committee to present a fair description of both sides of the discussion, which is what I hope to do.

James Esses, who started the petition, is a psychotherapist, and he impressed on me the benefit that good psychiatric intervention could have, without medicalisation. Puberty, he argued, is rarely a picnic for anyone—it can be confusing, uncomfortable, and sometimes miserable—but it is an essential developmental stage, and suppressing it pharmacologically could alter physical and cognitive development in ways we do not yet fully grasp. His argument is not to remove care for children experiencing gender incongruence, but to focus efforts on careful psychological support.

Others question the trial’s purpose, noting that puberty blockers have already been paused for new NHS patients with gender incongruence, following concerns about safety. They fear that authorising a new trial implies a level of confidence that the evidence base does not yet justify, arguing that enough data exists to recognise the potential harms, from reduced bone density to uncertain impact on brain development. Continuing could erode the safeguards that protect young people.