Studies of hormonal treatment or legal name change find higher prevalence than sex reassignment, with, for example a 2010 Swedish study finding that 1 in 7,750 adult natal males and 1 in 13,120 adult natal females requested a legal name change to a name of the opposite gender.Studies that measure transgender status by self-identification find even higher rates of gender identity different from sex assigned at birth (although some of those who identify as transgender or gender nonconforming may not experience clinically significant distress and so do not have gender dysphoria). A study in New Zealand found that 1 in 3,630 natal males and 1 in 22,714 natal females have changed their legal gender markers. A survey of Massachusetts adults found that 0.5% identify as transgender. A national survey in New Zealand of 8,500 randomly selected secondary school students from 91 randomly selected high schools found 1.2% of students responded "yes" to the question "Do you think you are transgender?". Outside of a clinical setting, the stability of transgender or non-binary identities is unknown.Research indicates people who transition in adulthood are up to three times more likely to be male assigned at birth, but that among people transitioning in childhood the sex ratio is close to 1:1. The prevalence of gender dysphoria in children is unknown due to the absence of formal prevalence studies. History
Neither the DSM-I (1952) nor the DSM-II (1968) contained a diagnosis analogous to gender dysphoria.
They noted a decrease in suicidal ideation among youth who have access to gender-affirming care and comparable levels of depression to cisgender peers among socially transitioned pre-pubertal youth. In its 2017 guideline on treating those with gender dysphoria, it recommends puberty blockers be started when the child has started puberty (Tanner Stage 2 for breast or genital development) and cross-sex hormones be started at 16, though they note "there may be compelling reasons to initiate sex hormone treatment prior to the age of 16 years in some adolescents with GD/gender incongruence". They recommend a multidisciplinary team of medical and mental health professionals manage the treatment for those under 18. They also recommend "monitoring clinical pubertal development every 3 to 6 months and laboratory parameters every 6 to 12 months during sex hormone treatment".A review published in Child and Adolescent Mental Health found that puberty blockers are fully reversible, and that they are associated with such positive outcomes as decreased suicidality in adulthood, improved affect and psychological functioning, and improved social life.More rigorous studies are needed to assess the effectiveness, safety, and long-term benefits and risks of hormonal and surgical treatments. For instance, a 2020 Cochrane review found insufficient evidence to determine whether feminizing hormones were safe or effective. Several studies have found significant long-term psychological and psychiatric pathology after surgical treatments.In 2021, a review published in Plastic And Reconstructive Surgery found that less than 1% of people who undergo gender-affirming surgery regret the decision.