In the first study of its kind in New Zealand, researchers found the use of the drugs for gender dysphoria first began in 2011, after the first guidelines were published. About 50 children received the drugs in that year. Usage increased steeply from 2014 to 2022 - at which point 400 children received a prescription - and had since fallen again.
Cumulative use of puberty blockers by 12-to-17-year-olds in New Zealand over this period was 1.7 times higher than the Netherlands, 3.9 times higher than Denmark, and between 3.5 and 6.9 times higher than England and Wales.
Lead researcher Charlotte Paul, an epidemiologist and public health expert at the University of Otago, said the relatively high use appeared to be be driven by three factors in New Zealand: easier access to assessment; a lower threshold for the diagnosis of gender dysphoria; and greater likelihood of recommending puberty blockers than other treatment options.
A fall in the number of first-time prescriptions in the last few years was possibly the result of clinicians and parents becoming aware of more cautious approaches being taken overseas, she said.
There were some limitations to the findings, which were published in the New Zealand Medical Journal today. It was not possible to know whether the medication was being prescribed for gender dysphoria or other conditions like precocious puberty. For this reason, researchers focused on prescriptions over the age of 12, when they were highly likely to relate to dysphoria.
Routine use of the drugs has been halted in the UK and they are now only available in clinical trials. France, Sweden and Finland have also taken steps to restrict puberty blockers or exercise greater caution in their use for young trans patients.
The British ban coincided with the Cass Review, a four-year investigation by paediatrician Dr Hilary Cass, which concluded that the evidence base for treating dysphoria with puberty blockers was weak.
Those findings have been challenged by some, including the union that represents 200,000 doctors, which said it contained “unsubstantiated recommendations” and that decisions about treatment should be made by clinicians, patients and families and not politicians.
The Ministry of Health is conducting its own review on the safety and reversibility of the drugs in order to develop clinical guidelines based on the latest evidence.
The ministry no longer publicly states that the medication is “safe and reversible” but endorses the guidelines of the Professional Association for Transgender Health Aotearoa, which says they are “considered to be fully reversible”.
The ministry’s review was initially scheduled to be finished at the end of last year. That was delayed until April and then August, so the Cass Review findings could be considered. It is yet to be released.
Paul would not comment on whether she believed New Zealand should follow the UK’s lead. But she said the “exceptionally high rate” of puberty blocker use and the potential for greater harm indicated that new guidelines should reflect “great caution”, at least until more was known about them.
She also echoed Cass’ plea for an end to the hostile and aggressive public discourse on the issue and for the issue to be handled collaboratively by professional organisations and with humility.
“I hope this might happen in New Zealand. Polarisation does not help vulnerable children or their parents.”
Expert reaction
Dr Rona Carroll, a GP and senior lecturer at the University of Otago, said it was not surprising that New Zealand had higher rates of prescribing puberty blockers.
“As the authors point out, the number of transgender young people does not appear to be increasing. Instead, the higher prescribing rates may be because young people feel safe expressing their gender and healthcare needs, have access to appropriate health services and live in a country where inclusion and respect for transgender individuals is growing.”
Carroll said New Zealand’s model of care was different from the centralised gender clinic model used in the comparison countries in the NZMJ paper, which often led to excessively long wait times for care.
“Our goal should not be to match UK prescribing rates, but rather to ensure that gender diverse children and young people receive accessible, individualised, and holistic care. The Pharmac data presented in the paper suggests that New Zealand is responding to this need.”
Professor Paul Hofman, a paediatric endocrinologist at the University of Auckland, said there were a number of caveats to the study, including potential under-reporting from other countries and the absence of information on what conditions the drugs were being prescribed for.
“Even with these caveats these data are concerning – we may be prescribing substantively more pubertal suppressive therapy than two European countries. Given this is an expensive therapy and the evidence for its efficacy in transgender youth remains relatively weak, it suggests that Pharmac should ask for a transgender diagnostic category for pubertal suppressive therapy use to confirm its prevalence in NZ.”
Professor Simon Denny, an adolescent and young adult physician, challenged the authors’ decision to frame the rise in puberty-blocking prescriptions as inherently problematic.
“Instead, this increase could reflect improved identification of gender dysphoria and better access to appropriate, evidence-based care for young people who need it,” said Denny, who previously worked at the Centre for Youth Health in South Auckland.
“To frame the data as alarming overlooks the reality that more individuals are actually receiving the care they need to live authentically and improve their mental well-being.”
He added: “While the article discusses the reversal of puberty blocker access in several countries, it does not address the robust criticisms of these policy changes. Many of these reversals were influenced by broader political and cultural contexts rather than conclusive scientific evidence. These complexities deserve mention to provide a more balanced view of the ongoing debates around gender-affirming healthcare.”
Isaac Davison is an Auckland-based reporter who covers health issues. He joined the Herald in 2008 and has previously covered the environment, politics and social issues.
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