Right-wing arguments for denying gender-affirming medicine to trans youth often center around puberty blockers, with multiple voices claiming that they do irreversible damage to the developing bodies of young children. A newly released systematic review from the highly respected journal JAMA Pediatrics offers strong evidence that these concerns are not based in scientific fact.
“Puberty blockers” is an umbrella term for a number of medications that have been widely prescribed to cisgender children for a variety of conditions since the 1980s. Even though trans youth now often access these medications, the vast majority of blockers are still prescribed to cisgender youth, with one study finding that between 2016 and 2025 82% of puberty blocker prescriptions went to cisgender youth.
These medications consist of a substance known as a “gonadotropin-releasing hormone agonist” (GnRHa agonist), which, when administered to youth, prevents the release of a hormone that stimulates a chain reaction, eventually culminating in the release of either estrogen or testosterone. Without that chain reaction, a youth’s puberty is effectively halted.
For years, right-wing voices—among them Hillary Cass of the Cass Review and anti-trans organizations like the Society for Evidenced-Based Medicine—have argued that this halt in puberty does damage to a youth’s developing bone structure. This damage, they claim, is never recuperated, even if a youth’s puberty resumes, leading to lifelong issues.
This rhetoric has been a main argument used by nations to justify sharply reducing youth access to gender-affirming medicine: in the UK, access to puberty blockers has been effectively stopped, and in Sweden it has been eliminated for all but the most “exceptional” cases. It has also been used by Republican politicians to justify bans on gender-affirming care for trans youth.
However, research conducted by Daniele Tienforti, Lorenzo Marinelli, and Giovanni Terrana shows that the claims of long-term bone damage are without merit. Tienforti and colleagues found that, as expected, puberty suppression does temporarily stop bone development in youth, but that once hormone replacement therapy is administered, youth catch back up to a position that is “not consistently statistically different” from that of their cisgender peers.
The authors of the study concluded that, once youth had been on hormone replacement therapy for a period of years, measures of bone development were “numerically lower than baseline but were generally not statistically different across most skeletal sites, suggesting at most a modest and uncertain shortfall in catch-up rather than a demonstrated persistent deficit.”
Tienforti and colleagues examined ten separate papers that explored the question of what, if any, long-term damage is done to youth by puberty suppression. These papers covered the experiences of 751 trans youth who had undergone puberty suppression with GnRHa agonist. This study was the first of its kind—never before had scientists undertaken a systematic review to synthesize the evidence of puberty blockers on the bone health of trans youth.
Tienforti’s study is known as a “systematic review,” which is generally seen to sit at the top of the “hierarchy of scientific evidence.” The term “systematic review” is an umbrella term for multiple kinds of research that comb through tens of studies in order to synthesize their findings and determine what this research collectively says. It is considered one of the most robust and trustworthy determinations of scientific fact.
Among other findings, Tienforti and colleagues found that shorter durations on GnRHa agonists lead to less loss of bone development, indicating that, when desired, youth should be allowed to move forward to hormone replacement therapy without undue delays.
The study’s authors also found a few variables that could help reduce bone density loss: “adequate vitamin D, balanced diet, and physical activity” all supported bone development, so Tienforti and colleagues recommended that doctors prescribing puberty blockers to trans youth encourage all three. They also cautioned that it is important for trans youth with an extremely low body mass index to get their weight up, as an “underweight” BMI was the most important factor in bone density loss.
As a part of their systematic review, Tienforti and colleagues rated the quality of each individual study that they examined via a widely used tool called the Newcastle–Ottawa Scale. Using a rating system across three different categories, researchers can award up to nine stars for studies that meet certain standards of analytical rigor. It is the most widely used tool of its kind.
Applying the Newcastle–Ottawa Scale to each study, Tienforti and colleagues found that the median score of the ten studies was a 7 stars out of 9, with two scoring 8 stars out of 9, indicating a low risk of bias and a high degree of methodological quality. Effectively, the studies reviewed in this paper are very trustworthy.
In addition to the findings of low risks to puberty blockers, there is much scientific evidence to support the benefits of giving youth access to puberty blockers and hormonal transition. Studies have found a reduction of suicidality, reductions in anxiety, depression, and negative thoughts, and reductions in mood disorders.
With so many right-wing voices using false statements about puberty blockers to take away trans rights—and also now even prominent Democrats turning on trans people in the run-up to the midterm elections—it is more important than ever to be clear on the facts: gender-affirming medical care is a medical necessity that greatly benefits the lives of trans people who desire it. These benefits are concrete and scientifically determined and should not be the subject of misleading political rhetoric or efforts to triangulate to win over voters.
Veronica Esposito (she/her) is a writer and therapist based in the Bay Area. She writes regularly for The Guardian, Xtra Magazine, and KQED, the NPR member station for Northern California, on the arts, mental health, and LGBTQ+ issues.
