The research for gender-affirming care is not in doubt. Here is where to find it.
A living reference guide to the clinical guidelines, peer-reviewed studies, and expert analyses that support gender-affirming care.
One of the things I hear most often, from families, from clinicians, from people trying to navigate their own healthcare, is this:
I know there is good research out there, but I cannot find it easily, and when I do find it, I am not sure how to use it.
This article is my attempt to fix that. I have gathered together the most important clinical guidelines from major professional bodies around the world, the key peer-reviewed studies on outcomes and mental health, and the most significant expert analyses of the Cass Review and what it got wrong. Everything is linked so you can read the original source. Everything is written so you can understand it without a medical degree.
Bookmark it. Share it with your GP. Send it to a sceptical relative. Take it to a school meeting. This is the evidence, and it is not in doubt.
I will keep this article updated as new research is published, so it stays useful over time.
A. Why this guide exists
In April 2024, the final report of the Cass Review1 was published for NHS England. Its central conclusion was that there is not a reliable evidence base upon which to make clinical decisions about gender-affirming care for young people. That conclusion has since been used to justify withdrawing and banning2 gender-affirming care in England and, by extension, in countries around the world that have looked to the UK for guidance.
The problem is that this conclusion does not accurately represent the state of the evidence. The Cass Review has been subject to detailed methodological criticism from some of the most experienced gender medicine clinicians on the planet. Its findings have been challenged in peer-reviewed journals including the New England Journal of Medicine. And the international professional bodies that set clinical standards in this field, bodies representing tens of thousands of doctors and researchers, have not changed their guidelines in response to it, because the evidence those guidelines are based on remains sound.
I am not saying the Cass Review was written in bad faith. I am saying it reached conclusions that do not hold up when you look carefully at the research it was based on, and that the harm caused by those conclusions has been, and continues to be, very real.
This guide gives you access to the actual evidence. Not a summary of someone else’s summary. The original sources, directly linked.
B. What the world’s leading medical organisations say
Every major professional body with expertise in paediatric endocrinology, adolescent medicine, psychiatry, and transgender health has produced clinical guidance supporting gender-affirming care for young people who need it. These are not fringe positions. These are the consensus standards of the medical community worldwide.
🌐 World Professional Association for Transgender Health (WPATH) — Standards of Care, Version 8 (2022)
The global clinical standard for the health of transgender and gender diverse people. SOC8 recommends puberty blockers and gender-affirming hormones for eligible young people following thorough assessment. Developed by more than 120 clinicians and researchers across multiple specialties worldwide.
The most comprehensive international clinical guideline. Updated from SOC7 (2012) with expanded evidence review.
🌐 WPATH and USPATH Position Statement on the Cass Review and NHS England (May 2024)
A formal joint statement in response to the Cass Review, stating that it “deprives young trans and gender diverse people of the high-quality care they deserve and causes immense distress and harm to both young patients and their families.” Also critiques the NHS England interim service specifications based on the Cass interim report.
Clinical practice guideline from the world’s leading specialist professional body for endocrinology and metabolism. Supports the use of GnRH analogues (puberty blockers) to suppress puberty in adolescents with gender dysphoria, followed by gender-affirming hormones when appropriate.
Widely cited as a foundational clinical standard. Updated position statement also available below.
🇳🇱 Endocrine Society — Position Statement on Transgender Health (2020)
The Society’s formal policy position, reaffirming that gender-affirming hormone therapy is safe and effective, and opposing restrictions on access to care.
AAP policy statement affirming gender-affirming care as medically necessary, opposing conversion practices, and calling on paediatricians to provide supportive, individualised care. Represents over 67,000 US paediatricians.
One of the most widely cited policy positions in paediatric transgender healthcare.
🇺🇸 UCSF Transgender Care — Guidelines for the Primary and Gender-Affirming Care of Transgender and Gender Nonbinary People (2016 (regularly updated))
Practical clinical guidelines from one of the world’s leading transgender health centres, covering primary care, hormone therapy, mental health, and surgery. Extensively referenced by clinicians worldwide.
🇦🇺 Australian Standards of Care and Treatment Guidelines for Trans and Gender Diverse Children and Adolescents (2018)
Published by the Royal Children’s Hospital Melbourne, these guidelines set out the Australian clinical standard for gender-affirming care in children and adolescents. Support staged, individualised care including puberty blockers and gender-affirming hormones.
The New Zealand clinical standard for gender-affirming healthcare across the lifespan, developed by clinicians and researchers at the University of Waikato. Particularly relevant given the current New Zealand puberty blocker ban and the judicial review in May 2026.
🇺🇸 The Fenway Institute, Boston — Care for Transgender Young People (Karger Publishers) (2020)
A comprehensive clinical review covering assessment, hormone therapy, surgical considerations, and mental health support for transgender young people, published in a peer-reviewed medical textbook.
C. What the research shows about mental health outcomes
This section contains the key peer-reviewed clinical studies on the mental health and wellbeing outcomes of gender-affirming care. These are the studies that matter most when someone tells you the evidence is weak or uncertain. Read them, link to them, share them.
📚 Mental Health Outcomes in Transgender and Nonbinary Youths Receiving Gender-Affirming Care Tordoff et al. (2022)
Key finding: Over 12 months, young people receiving puberty blockers or gender-affirming hormones had 60% lower odds of moderate to severe depression and 73% lower odds of suicidality compared to those not yet receiving treatment.
One of the most cited recent studies on gender-affirming care outcomes. Prospective design with validated mental health measures.
📚 Pubertal Suppression for Transgender Youth and Risk of Suicidal Ideation Turban JL, King D, Carswell JM, Keuroghlian AS. (2020)
Key finding: Adolescents who accessed pubertal suppression had 70% lower odds of lifetime suicidal ideation (adjusted OR 0.3) compared to those who wanted but did not receive it. One of the most powerful findings in the field.
Dr Jack Turban is one of the world’s foremost researchers in transgender youth mental health. This study used a large population-based dataset and has been extensively replicated.
📚 Access to Gender-Affirming Hormones During Adolescence and Mental Health Outcomes Among Transgender Adults Turban JL, King D, Li JJ, Keuroghlian AS. (2022)
Key finding: Access to gender-affirming hormones between the ages of 14 and 17 was associated with 60% lower odds of severe psychological distress and 62% lower odds of suicidality in adulthood compared to those who desired but did not receive treatment.
Extends the evidence on timing of care, earlier access to hormones is associated with better adult mental health outcomes.
📚 Psychosocial Functioning in Transgender Youth after 2 Years of Hormones Chen D, Berona J, Chan Y-M, et al. (2023)
New England Journal of Medicine
Key finding: After two years of gender-affirming hormone therapy, transgender youth showed significant improvements in appearance congruence and life satisfaction, and decreased depression and anxiety symptoms. Findings held across diverse demographic groups.
Published in the NEJM, one of the world’s highest-impact medical journals. A significant landmark study with prospective longitudinal design.
📚 Chest Reconstruction and Chest Dysphoria in Transmasculine Minors and Young Adults Olson-Kennedy J, Warus J, Okonta V, Belzer M, Clark LF. (2018)
JAMA Pediatrics
Key finding: Transmasculine young people who had chest surgery showed very low rates of regret and significantly improved body image and wellbeing. The regret rate was less than 1%.
Often cited by opponents of gender-affirming care as an argument against surgical intervention in young people. The actual data show the opposite, very high satisfaction and very low regret.
📚 Mental Health of Transgender Children Who Are Supported in Their Identities Olson KR, Durwood L, DeMeules M, McLaughlin KA. (2016)
Pediatrics
Key finding: Transgender children aged 3 to 12 who were supported in living in their affirmed gender had rates of depression and anxiety similar to those of cisgender children. Family support is protective.
One of the foundational studies on the importance of social affirmation and family support for trans children’s mental health.
📚 Mental Health and Self-Worth in Socially Transitioned Transgender Youth Durwood L, McLaughlin KA, Olson KR. (2017)
Journal of the American Academy of Child and Adolescent Psychiatry
Key finding: Socially transitioned transgender children (those living in their affirmed gender without medical intervention) had mental health outcomes comparable to cisgender peers, and significantly better than population norms for non-supported trans youth.
Social transition alone, which is entirely reversible, is associated with significantly improved mental health outcomes.
📚 Young Adult Psychological Outcome after Puberty Suppression and Gender Reassignment de Vries ALC, McGuire JK, Steensma TD, et al. (2014)
Pediatrics
Key finding: Young people who received puberty suppression followed by gender-affirming treatment showed levels of psychological wellbeing in young adulthood that were comparable to cisgender peers, with well-functioning social lives and no regret.
The foundational long-term outcome study from the Dutch group who developed the original puberty blocker protocol. Followed participants into adulthood.
📚 Association Between Recalled Exposure to Gender Identity Conversion Efforts and Psychological Distress and Suicide Attempts Among Transgender Adults Turban JL, Beckwith N, Reisner SL, Keuroghlian AS. (2020)
JAMA Psychiatry
Key finding: Transgender adults who recalled being subjected to conversion therapy had significantly higher rates of severe psychological distress and suicide attempts. This is important context: withholding affirming care and pressuring young people to “desist” causes measurable harm.
📚 Association of Gender-Affirming Hormone Therapy with Depression, Thoughts of Suicide, and Attempted Suicide among Transgender and Nonbinary Youth Green AE, DeChants JP, Price MN, Davis CK. (2022)
Journal of Adolescent Health
Key finding: Access to gender-affirming hormones was associated with 40% lower odds of depression and 44% lower odds of past-year suicidal ideation among transgender and nonbinary youth.
This is the Trevor Project study, using a very large sample of transgender youth.
📚 Gender-Affirming Hormone Therapy for Individuals with Gender Dysphoria Below 26 Years of Age: A Systematic Review and Meta-Analysis Miroshnychenko A, Roldan Y, Ibrahim S, et al. (2025)
Archives of Disease in Childhood
Key finding: Systematic review and meta-analysis of gender-affirming hormone therapy outcomes. Found consistent improvements in psychological wellbeing, quality of life, and gender dysphoria across studies, with an acceptable safety profile.
One of the most recent and methodologically robust systematic reviews. Published after the Cass Review.
📚 GROWING UP TRANSGENDER - Raising our trans child
Links to peer reviewed academic research by Horton, C. Articles are presented in three main categories: Healthcare, Education, Families.
D. Understanding the Cass Review
The Cass Review has been enormously influential, but it has also been the subject of significant expert criticism. These resources help you understand what the review did and did not find, and why so many experienced clinicians and researchers have taken issue with its conclusions.
📝 An Evidence-Based Critique of “The Cass Review” on Gender-Affirming Care for Adolescent Gender Dysphoria McNamara M, Baker K, Connelly K, Janssen A, Olson-Kennedy J, Pang KC, Scheim A, Turban J, Alstott A. (2024)
Yale Law School Integrity Project
Written by clinicians with 86 years of combined experience working with nearly 5,000 transgender young people. The critique finds that the Cass Review “obscures key findings, misrepresents its own data, and is rife with misapplications of the scientific method.” It also concludes that the review “takes an ideological position on care for transgender youth that is deeply at odds with the Review’s own findings.”
📝 The Future of Gender-Affirming Care: A Law and Policy Perspective on the Cass Review Aaron DG, Konnoth C. (2025)
New England Journal of Medicine, 392, 526–528
Published in the NEJM, this paper argues that the Cass Review “transgresses medical law, policy, and practice” and that its departure from standard evidentiary and procedural norms “can be understood best in the context of the history of leveraging medicine to police gender norms.”
📝 Critically Appraising the Cass Report: Methodological Flaws and Unsupported Claims Noone C, Southgate A, Ashman A, et al. (2025)
BMC Medical Research Methodology
A detailed methodological critique, peer-reviewed independently of the Yale group. Identifies specific flaws in how the Cass Review applied its evidence-grading framework, and documents unsupported claims in the final report.
📝 The UK’s Cass Review Badly Fails Trans Children Pearce R. (2024)
Dr Ruth Pearce, University of Glasgow, Lecturer in Community Development
Dr Pearce analyses the Cass Review’s approach to evidence and its treatment of transgender young people, concluding that it fails to meet the standard of care that trans children deserve and need.
📝 Biological and Psychosocial Evidence in the Cass Review: A Critical Commentary Various authors. (2024)
International Journal of Transgender Health
A detailed examination of how the Cass Review handled and in some cases mishandled the biological and psychosocial evidence relating to gender development and gender-affirming care.
E. Understanding randomised controlled trials and why they are not always the right tool
One of the most common arguments you will encounter is that there have been no randomised controlled trials (RCTs) of puberty blockers, and therefore the evidence is weak. I want to address this directly, because it is genuinely important to understand, and because the argument is often made in a way that is misleading.
An RCT works by randomly assigning participants to either receive a treatment or not receive it, without either the participant or the researcher knowing which group they are in. This design works well for treatments where we do not yet know which option is better, and where there is no ethical problem with withholding a treatment from the control group.
With puberty blockers, there is an ethical problem with the control condition. The children in the control group would go through puberty. For a trans girl, that means voice breaking, facial and body hair, and other male secondary sex characteristics developing. For a trans boy, that means breast development, menstruation, and the associated physical and psychological effects. We already have substantial evidence, including from the studies cited in Section C above, about what happens to gender-dysphoric young people who go through an unwanted puberty. The harm is measurable and it is significant.
Asking “has there been an RCT?” is a reasonable question in many contexts. But in this context, it functions as a way of setting an evidence standard that, by design, would require causing harm to children in the control group. That is not a neutral methodological request. It is an ethical problem dressed up as a scientific one.
The evidence base for gender-affirming care uses the study designs that are ethically appropriate for this population: longitudinal cohort studies, prospective studies with matched controls, large population-based datasets, and systematic reviews of all of the above. These designs produce good evidence. They are the same designs used to evaluate many other paediatric treatments for which RCTs would be unethical.
F. How to use this guide
If you are a parent who has been told by a GP or specialist that the evidence for puberty blockers is uncertain, you can share this guide with them, or ask them to look at the WPATH Standards of Care, the Endocrine Society guidelines, or the Tordoff or Chen studies specifically.
If you are a young person who has been refused care, or whose care has been withdrawn, this guide gives you the names and details of the studies that show why gender-affirming care matters for people like you.
If you are a clinician who wants to provide evidence-based care and is uncertain about the current regulatory landscape, the international guidelines in Section B set out what best practice looks like, and the studies in Section C provide the clinical rationale.
If you are a journalist, a policy maker, or someone who has been told that the Cass Review settled the science, Section D gives you the peer-reviewed responses from experts who have examined that claim carefully and found it wanting.
And if you are a person who simply wants to understand this better, because someone you love is trans and you want to know the truth, I hope this helps.
💬 I read every comment. If there is a study or guideline you think should be on this list, please message me.
About this article
This is a living document. I will update it as new research is published and as guidelines are revised. If you notice a broken link or an error, please let me know.
Dr Helen Webberley
Gender Specialist and Medical Educator | www.helenwebberley.com