Cass Defends Puberty Blocker Trial for Children Aged 11 and 12 as UK Ban Holds
Updated
Updated · BBC.com · Jun 22
Cass Defends Puberty Blocker Trial for Children Aged 11 and 12 as UK Ban Holds
2 articles · Updated · BBC.com · Jun 22
Summary
Children as young as 11 and 12 could join the Pathways puberty blocker trial from August, with Dr. Hilary Cass saying the study is essential to determine whether the drugs help or harm.
Cass argued her 2024 review found weak evidence behind puberty blockers and said skipping the trial could push young people toward unregulated treatment routes, including irreversible testosterone use at age 11.
King's College London tightened safeguards after a February pause, agreeing minimum ages of 11 for birth-registered females and 12 for birth-registered males, with monitoring of bone density, brain function and fertility.
The trial still faces legal action from campaigners who call it unethical and say children cannot give informed consent, while Conservatives want a Commons vote and trans advocates back the research but oppose the wider ban.
The UK's 2024 indefinite ban on puberty blockers remains in place for NHS and private prescribing, leaving the trial's evidence central to future policy decisions.
After a review found weak evidence, can one trial truly settle the science and ethics of youth gender medicine?
Is the surge in gender-questioning teens a medical crisis for a drug trial, or a social phenomenon needing different answers?
Puberty Blockers for Minors in the UK: The Pathways Trial Suspension, Cass Review, and Policy Shifts
Overview
The Pathways Trial was designed to study the use of puberty blockers in children and young people with gender dysphoria, planning to involve over 200 participants, some as young as eight. However, in February 2026, the Medicines and Healthcare Products Regulatory Agency (MHRA) intervened and paused the trial, citing serious regulatory concerns and prioritizing participant safety. This decision followed a letter from the MHRA and reflected growing scrutiny over the safety and evidence base for puberty blockers. As a result, the trial’s original design was deemed unviable, highlighting the need for stronger safeguards and a focus on protecting vulnerable children.