New Age Requirements for Puberty Blocker Trial
Children experiencing gender identity distress will need to be at least 11 years old to participate in the upcoming Pathways Trial, which aims to evaluate the safety and efficacy of puberty-blocking medications. This decision comes after the Medicines and Healthcare products Regulatory Agency (MHRA) previously halted the trial in February 2026 due to safety concerns and suggested a minimum age of 14, where none had been specified before.
Strengthened Safeguards and Participant Recruitment
Discussions between the MHRA and the research team have led to the implementation of “a number of safeguards,” including the new age criteria. While the initial recruitment of children is anticipated for August, ongoing legal challenges from some clinicians and advocacy groups, who question the trial’s safety and ethical considerations, could lead to delays.
It is important to note that the use of puberty blockers for individuals under 18 questioning their gender identity was banned in 2024. These drugs, also known as puberty suppressing hormones (PSH), are designed to postpone or prevent the onset of puberty.
Researchers from King's College London have agreed to postpone participant recruitment until after August 1st to allow for legal proceedings. They have also confirmed that no child will be enrolled in the trial without parental consent and that all participants must meet other eligibility requirements, including demonstrating a comprehensive understanding of the intervention, its potential benefits, and risks.
Trial Design and Ethical Considerations
The research team stated that they “always welcome scrutiny” of studies involving children and young people. In addition to setting a minimum age, they have enhanced patient information materials, though they confirmed “no major changes to the design or conduct” of the trial. The revised age limits are 11 for participants assigned female at birth and 12 for those assigned male at birth.
Furthermore, clearer guidelines are being introduced regarding when the drugs should be discontinued, such as in cases of concerns about bone density, cognitive function impact, or vaginal bleeding. More detailed information will also be provided on fertility preservation options for individuals.
The Pathways Trial, which received approval from UK regulators and ethics experts in November 2025, is designed to involve children under 16 who are experiencing gender distress and are currently accessing gender services. The study aims to investigate the drugs' effects on their physical, social, and emotional well-being.
Some medical professionals have questioned the necessity of this trial. Additionally, campaigners are pursuing legal action against the MHRA, the government, and other parties involved, arguing that the trial is unethical and that children cannot provide fully informed consent for a treatment that may affect their future fertility.
A 2024 review conducted by Dr. Hilary Cass concluded that gender medicine had been operating on “shaky foundations” regarding evidence for treatment. The ban on puberty blockers for under-18s was implemented following concerns about their safety raised by this review. Dr. Cass has since emphasized to the BBC the “vital” importance of the trial for puberty blockers in under-16s, to prevent “ongoing charlatans just handing out inappropriate drugs,” particularly in the context of private online sales.