The NHS has confirmed that it will fund a large-scale clinical trial investigating the potential benefits of puberty blockers for transgender adolescents. The trial comes on the back of findings from the controversial Cass Review which faced criticism from trans activists and healthcare specialists.

The study, which will be led by researchers at King’s College London, will receive over £10 million in NHS funding and aims to address alleged gaps in existing research on gender care for under-18s.  

The trial follows recommendations set out in the Cass Review, an independent report led by Dr Hilary Cass, which was published last year. The review cited a lack of high-quality evidence on the effects of puberty-suppressing hormones, leading to their ban across England, Scotland, Wales, and Northern Ireland.

However, the Cass Review has been widely criticised for not following established standards for evaluating evidence and for contravening “standard practice in scientific evaluations of medical research”. Described as “deeply flawed”, it has faced significant criticism from international medical bodies, including the British Medical Association and the World Association for Transgender Health (WPATH).

According to the NHS, the new trial aims to provide a clearer understanding of the impact of puberty blockers on young people’s physical, social, and emotional well-being.  

As part of the study, adolescents will be given puberty blockers for a period of just over two years, with the consent of their parents or guardians. Their development and well-being will be closely monitored to assess any potential benefits or risks associated with the treatment.

A comparison group of young people attending NHS gender services who do not take puberty blockers will also be studied to provide a broader picture of outcomes.  

Dr Hilary Cass has emphasised the importance of this research in improving gender care for young people. “This study will help fill crucial gaps in our knowledge about different interventions and address some of the uncertainty surrounding the impacts and effectiveness of puberty-suppressing hormones,” she said.  

Professor James Palmer, the NHS national medical director for specialised services, echoed this sentiment, stating that the research would be subject to strict ethical and regulatory approval.

The announcement of this trial comes against the backdrop of widespread backlash over the UK government’s decision to ban puberty blockers for under-18s last year. The indefinite ban, which is set to be reviewed in 2027, was introduced following the Cass Review’s findings.

The decision to prohibit puberty blockers has faced legal challenges, with advocacy groups initiating a pre-action legal claim against the government. The group argues that the ban was implemented unfairly and unlawfully, without consulting appropriate individuals or organisations.