Conservatives will attempt to block the NHS puberty blockers trial, Kemi Badenoch has announced, as she revealed plans to table amendments to the Health Bill now progressing through committee stage. The move follows the medicines regulator’s decision on Friday to allow the Pathways trial to resume with revised protocols.
Mrs Badenoch said: “Children must never be used as test subjects due to pressure from trans-activists and bureaucrats. The Government should halt the Pathways trial immediately. We already know the evidence for puberty blockers is weak. Yet ministers are pressing ahead with an experimental trial involving vulnerable children.”
She told the Telegraph: “When institutions fail to protect them, politicians have a duty to step in. If Labour refuses to stop this trial, I will ensure that the Conservatives will seek to amend the Health Bill to prevent it from going ahead.”
The Tory leader has been a vocal critic of gender-affirming care for children, previously stating that “no child is born in the wrong body” and describing the trial as “unethical”. She has argued that such care could be considered a “new form of conversion therapy”.
The Pathways Trial
The Pathways trial is a UK-wide clinical study investigating the effects of puberty-suppressing medication – gonadotropin-releasing hormone analogues (GnRHa) – on children and young people experiencing gender incongruence. It aims to recruit 226 participants under the age of 16, who will be randomly assigned to either commence treatment immediately or after a 12-month delay, with outcomes compared over two years. Linked studies, such as PATHWAYS CONNECT, will also examine cognitive function and brain development.
The research is funded by the National Institute for Health and Care Research (NIHR) and NHS England, and sponsored by King’s College London and South London and Maudsley NHS Foundation Trust. Researchers at King’s College London are scheduled to begin recruiting children from August 1.
The trial was established following the Cass Review, an independent report that found “remarkably weak” evidence for the safety and efficacy of puberty blockers in under-18s. The review recommended that such treatments should only be administered within a clinical trial setting. In December 2024, then Health Secretary Wes Streeting announced an indefinite ban on the sale and supply of puberty blockers for under-18s outside of clinical trials, describing previous use as a “scandal” and citing an “unacceptable safety risk” following advice from the Commission on Human Medicines that the drugs presented “unacceptable safety risk” to children. Despite the ban, Mr Streeting permitted the Pathways trial to continue as recommended by the Cass review to gather evidence on the drugs’ side effects.
In February 2026, the Medicines and Healthcare products Regulatory Agency (MHRA) suspended the trial after identifying concerns about “potentially significant” harm to participating children. The regulator highlighted “unquantified risk of long-term biological harms”, including risks to fertility, and suggested a minimum age of 14 for participants. Following scientific dialogue between the MHRA and King’s College London, protocol modifications were agreed, strengthening safeguards and establishing minimum age limits. Under the revised protocols, female participants must be at least 11 years old and male participants at least 12 years old.
On Friday, the MHRA confirmed that the revised protocols had been approved, permitting the study to proceed. The Pathways research team stated that “their health and safety is paramount” when conducting studies involving young people. A Department of Health and Social Care spokesman said: “The safety and wellbeing of young people is paramount. The MHRA has decided to strengthen and add additional safeguards for anyone who might take part in this trial. The review by Dr Hilary Cass concluded that not enough was known about the safety and efficacy of puberty-suppressing hormones. It is vital that decisions are based on clinical evidence. That is why the use of these hormones was paused and the trial set up to gather more data. The next steps for the trial will be set out in due course, subject to ongoing legal proceedings.”
Legal Challenges
Alongside the parliamentary challenge, the trial faces a separate legal bid to halt it. James Esses, a therapist and gender-critical activist, together with the Bayswater Support Group and detransitioner Keira Bell, have applied for an emergency injunction to prevent recruitment. They argue that the ethical approval process for the trial “contained serious flaws” and that it constitutes experimentation on vulnerable children. A High Court hearing has been set for July 27 to consider their application, which would halt recruitment until their judicial review is concluded.
Mr Esses told the Telegraph: “I always said from day one that our aim was to ensure that not a single child ended up ingesting this poison as part of the trial.”
Public opposition has also been expressed through a petition that gathered more than 146,000 signatures, leading to a Westminster Hall debate on the trial. Keira Bell, who began taking puberty blockers at the age of 16, is one of the claimants in the legal action. The Bayswater Support Group is an advocacy group for parents skeptical of their children’s transgender identities. The proceedings have been brought against the Department of Health and Social Care and the Health Research Authority.
