Puberty blockers as an intervention for adolescents with gender dysphoria: history and evidence

Event frequency and total participation In 2018 I discovered that the Tavistock’s Gender Identity Development Service (GIDS) had a study using ‘puberty blockers’—Gonadotropin-Releasing Hormone agonist (GnRHa)—to treat 44 teenagers (aged 12–15) diagnosed with gender dysphoria. The study had been launched in 2010, but no findings had been published. By submitting Freedom of Information requests and combing through reports to the Tavistock’s Board of Directors, I was able to piece together some of the study’s results. The researchers naturally expected puberty suppression to reduce gender dysphoria and increase psychological wellbeing, following results apparently achieved in the Netherlands. But no such positive effects were found among the Tavistock’s patients, and indeed some girls deteriorated. As this had been the first study to attempt to replicate the Dutch results, the failure to replicate called into doubt the worldwide adoption of puberty suppression for gender dysphoric teenagers.

My discovery first appeared on the blog Transgender Trend: ‘The Tavistock’s Experimentation with Puberty Blockers: Scrutinizing the Evidence’ (March 2019) and ‘An Update’ (July 2019). This was reported by the Daily Telegraph (8 March 2019) and BBC News (22 July 2019), and I was interviewed by BBC Newsnight (22 July 2019). I wrote a full paper on the origins and results of ‘The Tavistock’s Experiment with Puberty Blockers’ (29 July 2019) which became a chapter in Inventing Transgender Children and Young People (ed. Michele Moore and Heather Brunskell-Evans, Cambridge Scholars Press, 2019, pp. 40–55).

My first medical publication was a letter (Journal of Sexual Medicine, vol. 2019, p. 2043) about an article by the Tavistock’s researchers (Costa et al. 2015) which implied that patients undergoing puberty suppression had better psychological functioning than patients having only counselling. In fact, there was no statistically significant difference.

My complaint to the Health Research Authority about the Tavistock’s failure to publish outcomes from their study, along with the media coverage of my research, prompted its investigation. This investigation forced the Tavistock’s researchers to commit to belated publication of their experiment: they lodged their statistical analysis plan with the Health Research Authority just two days before the Authority sent me its report. I dissected its report for Transgender Trend (October 2019).

I was the first to publish the results of the Tavistock’s experiment: ‘Gender Dysphoria and Psychological Functioning in Adolescents Treated with GnRHa: Comparing Dutch and English Prospective Studies’ (Archives of Sexual Behavior, vol. 49, 2020, pp. 2231–36). My research was crucial to the landmark case of Keira Bell and Mrs A. versus Tavistock NHS Trust (2020) at the High Court of England and Wales, for which I was an expert witness. The judgment vindicated my findings, as I discussed on Transgender Trend (December 2020). Just one day after the judgment was delivered, the Tavistock’s researchers released a preprint with their results (Carmichael et al. 2020). My critique appeared on Transgender Trend (December 2020) and subsequently as a comment on the article published in PLOS One (February 2021).

Data from the Tavistock’s experiment, made available thanks to my complaint to the MHRA, was used in ‘Revisiting the Effect of GnRH Analogue Treatment on Bone Mineral Density in Young Adolescents with Gender Dysphoria’ (Journal of Pediatric Endocrinology and Metabolism, vol. 34, 2021, pp. 937–39). My analysis demonstrates that up to one in three patients ended up with such low bone density, compared to the norm for their sex and age, to put them at risk of osteoporosis.

My research on the Tavistock’s failures led me to investigate the origins of puberty suppression in the Netherlands, leading to ‘The Dutch Protocol for Juvenile Transsexuals: Origins and Evidence’ (Journal of Sex and Marital Therapy, vol. 49, 2023, pp. 348–68). This article has been viewed 97,000 times; one of its graphs is reproduced in the landmark Independent Review of Gender Identity Services for Children and Young People by Hilary Cass. An updated account was published as ‘The Technology of Puberty Suppression’ in Sex and Gender: A Contemporary Reader (ed. Alice Sullivan and Selina Todd, Routledge, 2023, pp. 175–93).

While I was conducting my own original research on puberty suppression, medical researchers at Oxford used a £700,000 grant to create a website promoting puberty suppression and advertising an offshore company that sold GnRHa. ‘Why are Health Talk and Oxford University Promoting GenderGP?’ I asked in The Critic (4 July 2022). The website was hastily edited to remove the advertising, and the controversy was reported in the Daily Telegraph (1 October 2022).

Exemplifying the poor quality of evidence in the field of gender medicine, an influential article used a large online convenience sample to claim that puberty blockers reduced suicidality (Turban et al. 2020). I wrote a critical online comment for the journal, Pediatrics, but it was rejected. An expanded version of my critique appeared as ‘Puberty Blockers and Suicidality in Adolescents Suffering from Gender Dysphoria’ (Archives of Sexual Behavior, vol. 49, 2020, pp. 2227–29; though labelled a ‘letter to the editor’, it underwent peer-review). I later forced Pediatrics to correct their article to acknowledge that one of the authors received money from a company that manufactures GnRHa. (Curiously, Pediatrics belatedly posted my online comment.)

A subsequent analysis by the same researchers used the same data to claim benefits for cross-sex hormones (Turban et al. 2022). The authors failed to report the estimated effect for puberty suppression, controlling for cross-sex hormones: now respondents who had taken puberty blockers reported no less suicidality than respondents who had not, contradicting their previous article. The authors also failed to notice that transgender males who took estrogen reported greater suicidality than those who did not (comment on PLOS One, January 2022; tables posted on figshare). My critique of this research was reported in Spectator World (20 June 2021).

‘How I Took on the Puberty Blocker Orthodoxy—and Won’ was recounted in the Sunday Telegraph (17 March 2024).


Additional media coverage: Podcast interviews:

Michael Biggs, Department of Sociology, University of Oxford