An NHS puberty blocker trial is “not ethical”, according to a Donald Trump-ordered review of children’s gender medicine.

The US federal review goes even further than Britain’s Cass Review by raising “serious concerns about medical interventions” of any form in children and teenagers.

Its Department of Health and Human Services concluded that “the overall quality of evidence is very low” to justify giving puberty blockers or cross-sex hormones to adolescents, including in trials such as the Pathways research planned by the NHS.

The highly critical review likens the trial of puberty blockers by the health service to trying to test the harms of jumping out of a plane without a parachute.

It was ordered by Mr Trump within days of taking office, having made gender ideology a central theme of his campaign in the run-up to the election.