Genspect Letter to Wes Streeting on the NHS PATHWAYS Puberty Blocker Trial

26 November 2025

The Rt Hon Wes Streeting MP
Secretary of State for Health and Social Care
Department of Health and Social Care
39 Victoria Street
London SW1H 0EU

Dear Mr Streeting,

Re: Urgent Concerns Regarding the NHS PATHWAYS Puberty Blocker Trial

I write as Founder and Executive Director of Genspect, an international organisation providing support to gender-distressed young people, their families, and detransitioners. Our Beyond Trans project is the only specialist support service for detransitioners in the UK.

Genspect urges you to stop the NHS PATHWAYS puberty blocker trial with immediate effect. The existing evidence already shows that the use of puberty blockers for gender-distressed children lacks a sound ethical or clinical justification. The failure even to complete the Cass Review’s recommended data linkage work for those already treated merely underscores this. The decision to proceed with this trial raises serious ethical and clinical concerns that cannot be justified by the current evidence base.

Proceeding Without Understanding Past Harms

The NHS proposes to medicalise 226 more children before establishing what happened to the estimated 2,000 young people already given puberty blockers by the Tavistock clinic. This represents a fundamental failure of medical ethics. Beyond Trans currently supports detransitioners who were harmed by these treatments, yet the trial protocol dismisses the data linkage study as unworkable due to “non-standardised data”. Given that PATHWAYS has £10 million in funding available, this rationale is simply inadequate.

Most troublingly, the words “detransition” and “regret” do not appear anywhere in the trial protocol, despite these being well-documented outcomes of puberty suppression. Detransition typically occurs 7–11 years after initial medicalisation, yet PATHWAYS will run for just two years. The trial is therefore structurally incapable of measuring the most significant long-term outcomes. Enclosed is our briefing pack, Puberty Blockers, Detransition and the NHS Trial, which includes personal testimonies from detransitioners and detailed analysis of the claims made about these drugs.

What the Evidence Actually Shows

The case against puberty blockers does not rest on gaps in the evidence – it rests on what the evidence clearly demonstrates. On any reasonable reading, the existing data are more than sufficient to conclude that no further trials exposing new cohorts of children to these drugs are warranted. The trial protocol itself documents extensive side effects: hot flushes, weight gain, sexual dysfunction, low mood, genital pain, anxiety, and compromised bone density. The Cass Review found no adequate evidence that puberty blockers reduce suicide risk or improve mental health. Indeed, the NHS’s own Early Intervention Study showed a significant increase in self-harm among participants after 12 months on blockers, with 34% experiencing mental health deterioration and a further 37% experiencing no change.

Perhaps most significantly, the natural history of gender distress points away from medical intervention. While 98% of young people who take puberty blockers proceed to sterilising cross-sex hormones, previous cohorts who did not receive blockers showed that 95% of gender-distressed youth became comfortable with their biological sex after natural puberty, with many growing up to be happily same-sex attracted. The evidence indicates that puberty blockers do not “buy time to think” but rather disrupt the very developmental process through which most young people would otherwise resolve their distress.

The trial’s design compounds these concerns. By adopting the ICD-11 diagnosis of “gender incongruence”, PATHWAYS will include children as young as ten who exhibit sex non-conforming interests and behaviours. The outcome measures ask children to rate their dissatisfaction with specific body parts and whether they would want to change them “through medical or surgical treatment” – a methodology that may prime participants towards medical solutions rather than measuring genuine therapeutic benefit.

Broad Professional Opposition

These concerns are shared by hundreds of medical professionals, safeguarding specialists, and academics. Genspect’s Memorandum of Understanding on the Role of Puberty in Adolescent Development has been formally adopted by numerous organisations internationally, establishing a shared ethical framework that opposes puberty suppression for gender-distressed minors. The MoU affirms that medically suppressing puberty infringes upon children’s right to an open future and calls for a shift towards developmentally appropriate care.

Our Statement of Concern directly opposes the PATHWAYS trial and calls for its cancellation. It has been signed by hundreds of individuals including current and former NHS clinicians, as well as consultant psychiatrists, psychologists, safeguarding specialists, academics, and medical professionals across multiple countries. These signatories share the view that the existing body of evidence already demonstrates that interfering with healthy pubertal development is not an appropriate response to gender-related distress, and that no further trials involving new cohorts should proceed at all. The Cass data linkage study is necessary in order to understand and acknowledge the full extent of harms already caused – not to justify further experimentation on children.

Both documents are available at ProtectingPuberty.com, where you can review the full text and signatory list.

What We Are Asking

In light of these serious concerns, we urge you to:

• Stop the PATHWAYS trial with immediate effect.
• Direct NHS England to complete and publish the Cass data-linkage outcomes, so that the outcomes for those already treated are fully understood and addressed, rather than obscured by further experimental research on new cohorts of children.
• Reallocate funding to develop and evaluate psychological and psychosocial interventions, as recommended by the Cass Review, which found these approaches showed significant improvements with no indication of adverse effects.
• Establish dedicated NHS services for detransitioners, including clinical care, rehabilitation, and long-term follow-up.

Young people experiencing gender distress deserve compassionate care that addresses their psychological difficulties without compromising their healthy development. The NHS has an obligation to understand the outcomes for those it has already treated – and to prevent further avoidable harm – rather than proceeding with experimental interventions on a new cohort of vulnerable children. The evidence is clear: puberty blockers disrupt natural recovery pathways, lead to lifelong medicalisation, and cause documented harm. We must not repeat past mistakes.

We would welcome the opportunity to discuss these concerns with you further.

Yours sincerely,

Stella O’Malley

Enc: Genspect UK Briefing: Puberty Blockers, Detransition and the NHS Trial

CC:
Baroness Merron, Minister of State for Mental Health
Stephen Kinnock MP, Minister of State for Care