England’s High Court has cleared the way for a major NHS-backed clinical trial examining puberty blockers in children experiencing gender incongruence, rejecting a legal bid to stop the research before recruitment begins.
The ruling allows researchers at King’s College London to enrol around 220 participants aged 11 to 16 in the PATHWAYS trial, a nationwide study designed to assess the safety and effectiveness of puberty-suppressing medication. The project follows recommendations from the 2024 Cass Review, which found there was insufficient high-quality evidence to support the routine use of puberty blockers in young people.
The legal challenge was brought by campaigners, including detransitioner Keira Bell, who argued the study exposed children to unacceptable ethical and medical risks. However, Justice Chamberlain ruled that the trial’s design included comprehensive safeguards, including specialist clinical assessments, parental consent, participant agreement, and regulatory oversight.
Participants in the study will be randomly assigned to begin puberty blocker treatment immediately or after a 12-month delay. Researchers will monitor outcomes over two years, with additional follow-up extending for a further two and a half years. The study will examine a wide range of measures, including mental health, quality of life, gender-related distress, physical development, cognitive function and treatment safety through clinical assessments, laboratory testing, imaging and standardised questionnaires.
The trial will be supported by two related research programmes. One will investigate brain development and cognitive function in a smaller group using advanced neuroimaging, while another will follow young people who do not receive puberty blockers to compare outcomes under alternative treatment approaches.
The PATHWAYS programme is intended to address longstanding concerns over the limited quality of evidence surrounding puberty suppression for children with gender incongruence. Its findings are expected to play a significant role in shaping future clinical guidance, healthcare policy and regulatory decisions in the United Kingdom and potentially overseas.
Despite the court’s decision, the issue remains highly contested. Supporters argue that robust clinical research is necessary to resolve ongoing uncertainty identified by the Cass Review, while critics continue to question whether it is ethically appropriate to randomise children into treatment and delayed-treatment groups.
Image credit: Talha Hassan
