Gender Incongruence: Puberty Suppressing Hormones

Emma Lewell Excerpts

Wednesday 30th April 2025 Westminster Hall

[Rebecca Paul (Reigate) (Con)]

I beg to move,

That this House has considered the potential impact of puberty suppressing hormones on children and young people with gender incongruence.

It is a pleasure to serve under your chairmanship, Ms Lewell. I am pleased to have the opportunity to shine a light on this important topic, one that impacts the health and wellbeing of some of the most vulnerable children in our country. This debate must be led by science, data and evidence, not by ideology, bias or belief. I will do my best to do that today.

The number of children and young people presenting to the UK NHS with gender distress has increased year on year since 2009, with an exponential rise in 2014. What is behind the increase among Generation Z is unclear and the reasons are likely to be multifaceted. It is speculated that the factors may include 24/7 internet access, increased acceptance of trans identities, or even peer, social and cultural influences.

Over the last 20 years we have seen groups such as Stonewall and Mermaids call for better access to treatment and increased rights for trans people. Large corporates have gone big on diversity and inclusion to boost their brands, impactful TV dramas centring trans stories, such as “Butterfly”, have been widely viewed, and the public sector, from the NHS to the police, has been flying the progress flag at every opportunity. So it can be no surprise that gender identity is at the front of young people’s minds in a way that it simply was not when I was growing up.

In 2009, only 51 patients were referred to GIDS—the NHS gender identity development service for children—of whom two thirds were male. In 2016, there were 1,766 referrals and two thirds of them were female. That is quite the change. There has been an overall surge in the number of children suffering gender distress, but the increase is especially notable among girls; we also see over-representation of neurodiversity, mental health issues and trauma in this group. To put it another way, these children are much more likely to have been in care, to suffer with anxiety and depression, to be autistic and to have been abused. It is a group of incredibly vulnerable children.

GIDS was established in 1989. Its main approach to treatment at that time was therapeutic—referred to as watchful waiting. Early studies from the 1980s showed that in around 85% of cases, the gender incongruence or distress ceased in the child after going through puberty. Later studies reached a similar conclusion, with between 67% and 90% desisting after puberty. Only a small cohort of children continued to experience gender dysphoria or incongruence after puberty, and it was that small group who would likely adopt a permanent trans identity in adulthood.

Everything changed with the emergence of the Dutch protocol, which involved the use of puberty blockers from early puberty. Puberty blockers are gonadotropin-releasing hormone analogues, which supress oestrogen production in girls and testosterone in boys. They are licensed for use in children with precocious puberty—when puberty starts much too early and it is beneficial to suppress it until a more normal developmental time and age—but in the case of gender dysphoria they are used to delay or even indefinitely stop natural pubertal development and maturation, and it is important to note that puberty blockers are not licensed for that purpose.

The original rationale for using puberty blockers to treat gender dysphoria was to press pause on puberty and give children time to think, but for some the aim was also to increase the chances of a child passing as a member of the opposite sex in adulthood. GIDS started trialling puberty blockers in the UK after 2011. The preliminary results in 2015-16 did not demonstrate psychological benefits, with some of the females suffering a worsening of symptoms, including higher incidence of wanting to hurt or kill themselves. The results of the study, which were not formally published until 2020, demonstrated no statistically significant improvement in gender dysphoria or mental health outcomes.

It is also important to remember the early studies that told us that in the majority of cases, going through puberty could relieve gender distress. It follows, therefore, that stopping or delaying puberty using medication could derail that natural desistence, essentially locking in or prolonging the gender distress, rather than allowing it to naturally resolve.

One would think that, in the absence of any evidence of benefit from puberty blockers, the NHS would have stepped back from using them after the trial. Furthermore, the high numbers of autistic, traumatised, mentally unwell and same-sex attracted youth in the group of children referred should have rung alarm bells loudly, but no; instead, puberty blockers and cross-sex hormones were routinely made available to an even broader group of children, including those with neurodiversity and complex mental health presentations.

An independent systematic review of published studies on puberty blockers, of which there were 50, was undertaken by the University of York as part of the Cass review. It was found that puberty blockers do indeed suppress puberty effectively. It was also found that, given that most children progress on to cross-sex hormones after starting puberty blockers, the main objective of pausing development is not achieved. No reduction in gender dysphoria or improvement in body satisfaction was demonstrated, and there was limited evidence of positive mental health outcomes.

Worryingly, bone density in those taking puberty blockers was compromised, and height gain may lag behind normal. In the case of biological males, it can make vaginoplasty more difficult in future, due to insufficient penile growth, forcing the use of gut tissue instead. The Cass review reports:

“There seems to be a very narrow indication for the use of puberty blockers in birth-registered males…in order to stop irreversible pubertal changes. Other indications remain unproven at this time.”

I take that to mean that those drugs have been given to young girls, not because they benefit them specifically, but because they might benefit a very small group of males. Professor David Bell, a retired consultant psychiatrist at the Tavistock, and Dr Sinead Helyar, a clinical trial nurse, also warned of the potential harms in a recent article.

“Current known and potential harms of puberty blockers are multi-fold and include a reduced bone density and early-onset osteoporosis, brain swelling and concerns around impairment of future sexual functioning and ability to form emotional relationships. A recent review of the impact of suppressing puberty on neurological function highlighted that adolescence is a critical window of neurodevelopment and puberty plays a critical role in this process. The author concluded that suppression of puberty impacts brain structure and the development of social and cognitive functions, in which the effects are complex and often sex specific.”

The over-representation of same-sex attracted girls and boys in the group of children being treated with puberty blockers is particularly worrying. In a study in the Netherlands of 70 patients given puberty blockers between 2000 and 2008, 89% were same-sex attracted, and most of the rest were bisexual. The same pattern was seen in most of the other trials, with the majority of the children growing up to be same-sex attracted adults. A paper from GIDS in 2016 reported 89% of the biological girls being either same-sex attracted or bisexual.

Why would same-sex attraction be over-represented in that way? Could gender distress be symptomatic in some cases of struggling with sexuality? Is sufficient emphasis put on reassuring those young adolescents about their sexuality, to establish if the gender distress is linked or separate; or is our society’s hyperfocus on gender identity and gender conformity putting them on an unnecessary medical pathway to change their body? Keira Bell, who has now detransitioned, says,

“I became attracted to girls. I had never had a positive association with the term ‘lesbian’ or the idea that two girls could be in a relationship. This made me wonder if there was something inherently wrong with me. Around this time, out of the blue, my mother asked if I wanted to be a boy, something that had not even crossed my mind.”

The Cass review received several reports from parents of biological females that their child had been through a period of trans identification before recognising that they were, in fact, a lesbian. That begs the question: why are so many young lesbians being medically transitioned?

Before I move on to my questions to the Minister, it is important to note that almost all the children and young people who take puberty blockers go on to take cross-sex hormones. I raise that because it links the two treatments. The impact of puberty blockers cannot be looked at in isolation, because cross-sex hormones may lead to further surgeries, lifelong medication, and loss of fertility and sexual function. These are catastrophic impacts. How can a prepubescent child really understand what never experiencing an orgasm means and the impact that could have on their future relationships, or indeed what losing the opportunity to have children could mean?

It is very apparent that the lack of solid long-term data on outcomes for patients who are treated with puberty blockers is problematic. No doctor should prescribe something in the absence of strong evidence of its effectiveness and a clear understanding of the side effects. In May 2024, the previous Government temporarily banned the use of puberty blockers for the treatment of gender incongruence and gender dysphoria in under-18s, following the Cass review’s findings of insufficient evidence to show they were safe and effective, and this ban was made permanent by the current Secretary of State for Health and Social Care in December 2024. In the light of everything that I have set out today, I fully support that decision: it is sensible, has full regard to the data, and puts the safety and wellbeing of children first.

It is also important to note campaigners’ claim that suicides among young patients with gender dysphoria increased due to puberty blocking drugs previously being restricted, following the High Court decision in the Bell v. Tavistock case, has been disproved by Professor Louis Appleby’s investigation and report, published on 19 July 2024, in which he confirmed that the data did not support such assertions. He concludes that:

“The way that this issue has been discussed on social media has been insensitive, distressing and dangerous, and goes against guidance on safe reporting of suicide. One risk is that young people and their families will be terrified by predictions of suicide as inevitable without puberty blockers.”

At the same time that the Secretary of State announced the permanent ban on puberty blockers, he announced that a clinical trial would be set up in 2025 to examine the use of puberty blockers, in order to establish a clear evidence base for the use of this medicine in gender incongruence. The £10.7 million trial, called Pathways, will be carried out by a team at King’s College and is due to run until 2031. Over two years, it will track:

“the physical, social and emotional wellbeing”

of young people who want to delay puberty, and whose parents and the gender service agree with this treatment option.

I will be grateful to the Minister for an update on the trial and how she intends to ensure that children are not physically or psychologically harmed. A trial of this nature of a drug that is unlicensed for gender incongruence raises many ethical concerns. In the words of Professor David Bell and Dr Sinead Helyar:

“The first duty of any clinician inside or outside of a clinical trial is to ‘do no harm.’”

Can there ever be a situation where it is ethical to run such a trial when the harms could be significant? It is important to remember that the children who would participate in this trial are physically healthy children who stand to have worse health by the end of it. This trial is in no way similar to a clinical trial for a cancer drug, where the patient is seriously unwell at the beginning of the trial.

Secondly, approximately 9,000 children and young people were treated by GIDS over the years, which provides a plentiful supply of data about the long-term outcomes for those who took puberty blockers and those who did not. Would the Minister please clarify matters and explain why a new trial is needed, given this abundance of data? Will she please provide an update on the exercise that is currently under way to obtain more data?

Thirdly, the current trial only proposes to look at outcomes over a two-year period. To put that into context, a child who starts puberty blockers at the age of 13 will only have their outcomes followed and assessed until the age of 15. That is not long enough to understand medium and long-term outcomes. A positive result for a 15-year-old might look very different for a 25-year-old, when physical health, sexual function and fertility are likely to be more important and relevant to them than when they were 15. Does the Minister agree that two years is not a sufficient timeframe to properly evaluate the impact of puberty blockers on physical and mental health? If this trial goes ahead, will she commit to funding and ensuring that there is long-term follow-up of these children into adulthood?

Fourthly, how many children will the trial be limited to, and what criteria will be used to determine which children are eligible and which are not? Is it possible that all eligible children will be included and prescribed puberty blockers as part of the trial? How many children in total does the Minister expect to take part in the trial over its duration? How will the trial establish an appropriate control group? Fifthly, given that gender nonconformity sometimes correlates with same-sex attraction in adulthood, how will the trial safeguard those children who may simply be uncomfortable with their sexuality rather than experiencing true gender distress?

Sixthly, given the high rates of progression to cross-sex hormones following puberty blockers, will only children who agree not to progress to cross-sex hormones be accepted on to the trial, so that the impact of the puberty blockers on outcomes can be seen in isolation? If the answer is no, given the corresponding likelihood of impaired sexual function and loss of fertility, which are monumental ramifications, how will the children taking part in the trial be able to give consent?

Finally, will the Minister please provide details of other trials that have been approved for paediatric medical interventions with equivalent or similar diagnostic uncertainty, to reassure the public that moving forward with a trial in this situation has precedent? I look forward to hearing the Minister’s answers and thank everyone for attending this debate.

[Emma Lewell (in the Chair)]

I remind Members that this debate will run until five past 6. I will be calling the Front Benchers at 5.45 pm, so I ask Members to keep their contributions to five minutes.