Belgium and the Netherlands have become the latest countries to question the use of puberty blockers on children after the Cass Review warned of a lack of research on the gender treatment’s long-term effects.

Britain has become the fifth European nation to restrict the use of the drug to those under 18 after initially making them part of their gender treatments.

Their use was based on the “Dutch protocol” – the term used for the practice pioneered in the Netherlands in 1998 and copied around the world, of treating gender dysphoric youth using puberty blockers.

The NHS stopped prescribing the drug, which is meant to curb the trauma of a body maturing into a gender that the patient does not identify with this month.

In Belgium, doctors have called for gender treatment rules to be changed.

Research into impact

“In our opinion, Belgium must reform gender care in children and adolescents following the example of Sweden and Finland, where hormones are regarded as the last resort,” the report by three paediatricians and psychiatrists in Leuven said.

Figures from the Netherlands and the United Kingdom show that more than 95 per cent of individuals who initiated puberty inhibition continue with gender-affirming treatments,” the report by P Vankrunkelsven P, K Casteels K and J De Vleminck said.

“However, when young people with gender dysphoria go through their natural puberty, these feelings will only persist in about 15 per cent.”

The report was published after a 60 per cent rise in the number of Belgium teenagers taking the blockers to stop the development of their bodies. In 2022, 684 people between the ages of nine and 17 were prescribed the drug compared to 432 in 2019, the De Morgen newspaper reported in 2019.

Pressure is also building in the neighbouring Netherlands to look again at their use. The parliament has ordered research into the impact of puberty blockers on adolescent’s physical and mental health.

Dutch protocol

The Telegraph understands that the Amsterdam Center of Expertise on Gender Dysphoria, where the protocol originated, is set to make a statement on the use of puberty blockers next week.

“I too thought that the Dutch gender care was very careful and evidence-based. But now I don’t think that any more,” Jilles Smids, a postdoctoral researcher in medical ethics at Erasmus University in the Netherlands, told The Atlantic.

Attitudes in the Netherlands have hardened against trans rights, with a bill to make it easier for people to legally change their gender being held up in parliament.

The Cass Review said that the NHS had moved away from the restrictions of the original Dutch protocol, and researchers in Belgium have also demanded those restrictions be reintroduced.

Belgium is regarded as one of the most trans-friendly countries in Europe. A minister in the government is transgender and people have been able to legally change their gender without a medical certificate for the past five years.

But the hard-Right Vlaams Belang party is currently leading the polls ahead of national and European elections in June.

It has called for “hormone therapy and sex surgery to be halted for underage patients until clear and concrete research has been carried out.”

‘Greatest ethical scandals’

In March, a report in France described sex reassignment in minors as potentially “one of the greatest ethical scandals in the history of medicine”.

Conservative French senators plan to introduce a bill to ban gender transition treatments for under-18s.

On Monday, the Vatican’s doctrine office published a report that branded gender surgery a grave violation of human dignity on a par with euthanasia and abortion.

Finland was one of the first countries to adopt the Dutch protocol but realised many of its patients did not meet the Protocol’s strict eligibility requirements for the drugs.

It restricted the treatment in 2020 and recommended psychotherapy as the primary care.

Sweden restricted hormone treatments to “exceptional cases” two years later. In December, Norwegian authorities designated the medicine as “under trial”, which means they will only be prescribed to adolescents in clinical trials.

Denmark is finalising new guidelines limiting hormone treatments to teenagers who have had dysphoria since early childhood.

In 2020, Hungary passed a law banning gender changes on legal documents.

“The import and the use of these hormone products are not banned, but subject to case by case approval, however, it is certain that no authority would approve such an application for people under 18,“ a spokesperson told The Telegraph.

In August, Russia criminalised all gender reassignment surgery and hormone treatments.