LONDON — A major clinical trial investigating the use of puberty blockers for children with gender dysphoria has been paused indefinitely, the UK government announced on Saturday, amid fresh concerns raised by regulators about the wellbeing of young participants.
The Department of Health and Social Care (DHSC) confirmed that recruitment for the Pathways trial, led by researchers at King's College London, will be postponed until outstanding issues are resolved. The pause follows new alerts from the Medicines and Healthcare products Regulatory Agency (MHRA), which flagged "new concerns directly related to the wellbeing of children and young people." A DHSC spokesperson stated that scientific dialogue is now underway with the trial sponsor, and preparations have been halted while clinicians interrogate the evidence.
The trial, which aimed to recruit around 226 young people aged between 10 and almost 16, was designed to address gaps in the evidence base for puberty blockers—medications that temporarily halt physical changes associated with puberty. These drugs have been a contentious topic in pediatric gender care, with advocates arguing they provide crucial time for children to explore their identities, while critics warn of potential long-term health risks and ethical issues around consent.
The decision to pause comes just months after the trial's launch, which stemmed from recommendations in the Cass Review, a comprehensive 2024 inquiry into youth gender services led by senior pediatrician Baroness Hilary Cass. The review, commissioned by the National Health Service (NHS), found the existing research on puberty blockers to be of "poor" quality, describing the evidence for their benefits as "very weak." Despite this, Baroness Cass argued that a properly supervised trial represented "the only way forward," especially given the passionate beliefs of clinicians, children, and families in the drugs' positive effects.
"Even though my report uncovered a very weak evidence base for these benefits, a trial was the only way forward," Baroness Cass said in comments reported earlier this year. She emphasized that allowing such a study under strict oversight was preferable to the alternative of children accessing unregulated puberty-suppressing drugs via the dark web.
The pause has drawn mixed reactions, highlighting deep divisions in the ongoing debate over transgender youth healthcare. Campaigners, including author J.K. Rowling, who has been vocal in her opposition to certain aspects of gender-affirming care, welcomed the news. Rowling, along with other activists, had initiated legal action against the government earlier this month, labeling the trial "an unethical experiment on children who can't give meaningful consent."
On the other side, supporters of the trial, including medical experts involved, stressed its scientific importance. A spokesperson for King's College London, the institution set to oversee the study, reaffirmed their commitment to youth wellbeing. "The wellbeing and health of young people with gender incongruence and their families has been, and will remain, our priority," the spokesperson said. They added that the trial, crafted by "world-leading academics with scientific rigour at its core," aims to build a stronger evidence base to inform future decisions for young people and clinicians.
"That rigour and ongoing scientific discussion is important for any clinical trial, particularly one as complex as Pathways," the King's College statement continued. The team plans to collaborate closely with the MHRA during the review process.
The DHSC spokesperson elaborated on the timeline, noting that recruitment will remain on hold until the concerns are addressed with King's College and it is determined that proceeding is "both safe and necessary." The announcement was made public on February 21, 2026, at 5:47 a.m. UK time, underscoring the urgency of the regulatory intervention.
Political figures have also weighed in, reflecting broader ideological tensions. Conservative leader Kemi Badenoch had previously urged Health Secretary Wes Streeting to halt the trial entirely, writing in a letter that it must be stopped "before more damage is done to children." Badenoch's stance aligns with conservative critiques of what she and others see as rushed medical interventions for minors.
Streeting, however, expressed personal reservations while defending the initial go-ahead. "I was uncomfortable with puberty blockers being given to children," he admitted in recent statements. Nonetheless, he maintained that following expert advice necessitated the trial, calling it "the right thing to do." The Labour government's position has been caught between scientific recommendations and public backlash, with the pause now providing a temporary reprieve.
The Cass Review, published in April 2024 after an 18-month investigation, painted a stark picture of the UK's gender identity services for youth. It reviewed thousands of cases and consulted hundreds of experts, concluding that the evidence supporting puberty blockers—used to treat gender dysphoria by delaying puberty—was inadequate to justify widespread use. The report led to significant NHS policy changes, including restrictions on blockers outside of research settings and a push for more holistic, non-medical approaches to care.
Baroness Cass's findings echoed international concerns, including those from the World Professional Association for Transgender Health (WPATH), which has faced scrutiny over its standards of care. In the UK, the review prompted the closure of the Tavistock GIDS clinic in London, the country's sole youth gender service at the time, amid allegations of overly affirmative practices. The Pathways trial was envisioned as a rigorous, randomized controlled study to fill these evidentiary voids, potentially involving participants from multiple NHS trusts across England.
Legal challenges have intensified the scrutiny. Rowling's involvement, alongside groups like the Society for Evidence-Based Gender Medicine, argues that the trial violates ethical norms by exposing vulnerable children to experimental treatments without sufficient safeguards. Their lawsuit, filed in the High Court, seeks an injunction and has garnered support from parents and detransitioners who report regret over past interventions.
Despite the pause, the trial's proponents argue it remains essential for advancing knowledge. Dr. Polly Carmichael, a lead consultant in pediatric gender services who contributed to the Cass Review, has previously noted that without better data, clinicians are left navigating a landscape of uncertainty. The MHRA's concerns, described as newly emerged during protocol reviews, reportedly center on psychological impacts and long-term monitoring, though specifics remain under wraps pending the ongoing dialogue.
As the review process unfolds, the pause could extend for months, delaying what was hoped to be a landmark study. For families awaiting access to gender care, the development adds to frustrations in a field already strained by clinic backlogs and policy shifts. The DHSC has not specified a resumption date, but officials indicated that any restart would require unanimous clinical consensus on safety.
This episode underscores the evolving nature of transgender healthcare policy in the UK, where scientific inquiry intersects with ethical, legal, and political debates. With the Cass Review's recommendations still rippling through the system, the outcome of the MHRA's assessment could shape future access to puberty blockers not just in Britain, but influence global standards as well.
For now, the young people and families at the heart of the Pathways trial wait in limbo, as experts work to balance innovation with caution in one of medicine's most sensitive domains.