Evaluations › Biggs · Last reviewed 2026-05-16
Biggs — puberty blocker overview
Summary
Dr Michael Biggs (Department of Sociology, University of Oxford) published a series of peer-reviewed articles and analyses on the Dutch Protocol and the Tavistock GIDS "Early Intervention Study". His work documents discrepancies between internal GIDS data and what was publicly reported, and revisits the methodology of de Vries 2011 / 2014.
Publications (selection)
- Biggs M. The Tavistock's experimentation with puberty blockers: scrutinizing the evidence. Int J Transgender Health. 2020;23(4):349–53.
- Biggs M. Suicide by clinic-referred transgender adolescents in the United Kingdom. Arch Sex Behav. 2022;51:685–90.
- Biggs M. The Dutch Protocol for juvenile transsexuals: origins and evidence. J Sex Marital Ther. 2023;49(4):348–68.
Main findings
- Internal GIDS data showed no consistent psychological improvement in GnRHa participants; publication of these results was delayed.
- De Vries 2014 contains methodological weaknesses that have not been explicitly worked through in earlier literature.
- Suicide incidence among GIDS-referred youth has, despite public reporting, not turned out to be higher than in comparable populations.
See also
- Criticised study: de Vries 2014 — Amsterdam study
- Criticised earlier study: de Vries 2011
- Central clinical context: Tavistock GIDS (UK)
- Broader methodological criticism: Methodological criticism
- Attrition analysis: Sample size and attrition
- Replication problems: Replication attempts
- People register — Biggs and GIDS figures.
- International comparison — policy in table form.
- Timeline — Biggs publications in chronology.
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