Dr. Hilary Cass, author of a comprehensive review on gender-affirming care for children, has voiced strong support for the Pathways clinical trial examining the use of puberty blockers, stating it is crucial for reducing harm to young people.
"I am absolutely convinced that more children will be harmed if we don't do the trial than if we do," Dr. Cass told the BBC. Her comments come in response to pressure from campaigners and some politicians seeking to halt the research program. Concerns had been raised particularly after the announcement that children as young as 11 could be recruited.
The trial, to be conducted by researchers at King's College London (KCL), has implemented stricter safeguards and established minimum age limits: 11 for individuals registered female at birth and 12 for those registered male at birth. Recruitment is slated to begin in August, pending the resolution of ongoing legal action.
Dr. Cass's 2024 review highlighted the limited evidence supporting the use of puberty blockers, which led to the recommendation for this research. Previously, the National Health Service (NHS) prescribed these medications to individuals under 18 for gender care. However, in 2024, the UK government implemented a nationwide ban on their private and NHS prescription for gender care for minors.
Dr. Cass suggested that some of the perceived risks associated with puberty blockers may have been exaggerated, as the actual harms are not yet fully understood. She emphasized the trial's necessity in determining the efficacy and safety of these drugs, noting that participants will undergo close monitoring, with interventions halted if any concerns arise. The research will assess the physical, social, and emotional well-being of participants, including checks on bone density, brain function, and fertility.
She argued that without a structured trial, young people might resort to "unregulated and dangerous routes" for medication, potentially leading to irreversible treatments like testosterone at an early age. "Today we have young people turning up in the clinics on testosterone at 11, which we know is irreversible," she stated. "It may be that if they were prescribed puberty blockers instead, that would give more time for the therapist to work with them and perhaps come to a different solution than a long-term life on medication."
Testosterone, a masculinizing hormone, is not approved for gender treatment in children under 16 in the UK. Puberty blockers, also known as puberty-suppressing hormones (PSH), are designed to temporarily pause the onset of puberty.
Health Secretary James Murray informed Parliament that clinical evidence is paramount for future decision-making. He expressed personal unease regarding the matter but stated that following clinical advice and basing decisions on evidence, coupled with assurances about participant safeguards, is the appropriate path forward.
The trial, initially announced in November, was paused in February when medical regulators proposed a minimum age of 14. KCL researchers subsequently agreed on the lower age limits after careful deliberation.
Legal action against the trial has been initiated by groups such as the Bayswater Support Group, which represents parents cautious about medical interventions for their gender-questioning children. These groups contend that the trial is unethical and that children cannot provide fully informed consent for a procedure that might impact future fertility. A spokesperson for the Bayswater Support Group stated the trial risks irreversible harm and fails to address fundamental questions about puberty blockers.
In contrast, Chay Brown, Healthcare Director of the trans advocacy group TransActual, views the trial as the sole legal avenue for young people to access puberty blockers. TransActual advocates for the reversal of the ban and for timely, holistic care for all transgender individuals.
Dr. Cass maintains that the issue requires resolution through scientific and clinical consensus, asserting that young people and their families have faced prolonged shortcomings in NHS services.