13 General introduction 1 literature. A first approach in pre-pubertal children is described as the ‘therapeutic model’ (Dreger, 2009). This approach consists of direct or indirect efforts to reduce the child’s cross-gender identification. A second approach is described as the ‘affirmative model’ (Ehrensaft, 2012). This approach considers all outcomes of gender identity to be equally desirable and valid. Furthermore, it allows children who express the desire to socially transition2 to do so after careful counselling. The third approach in pre-pubertal children is described by some as ‘watchful waiting’: parents are advised to keep options open about their child’s long-term gender identity and to avoid early social transition, without direct efforts to ‘prohibit’ the gender incongruent behaviour of their child (Drescher & Byne, 2012; Turban, de Vries, Zucker, & Shadianloo, 2018b). Treatment for pre-pubertal children regarding this approach is predominantly psychological, focusing on, if any, the child’s concomitant behavioural and emotional struggles and providing parent counselling (de Vries & Cohen-Kettenis, 2012). Of these three described approaches, ‘watchful waiting’ is the most commonly advised in the Netherlands in pre-pubertal children with gender incongruent experiences. Not all pre-pubertal children with gender incongruent experiences, will be transgender adults. Of the pre-pubertal children referred to a gender identity clinic, only a minority (2-33%) return around or after the onset of puberty with the desire to undergo genderaffirming medical treatment (GAMT) (Ristori & Steensma, 2016). In contrast to these findings of clinical follow-up, a recent convenience sample of socially transitioned children showed very few retransitions after five years (Olson, Durwood, Horton, Gallagher, & Devor, 2022). In addition, not all (young) adults referred to a gender identity clinic with the desire to undergo GAMT, have had gender incongruent experiences as a child or have expressed a desire to be of a different gender as a child. Gender diversity thus may have several developmental paths (Bungener & de Vries, 2022). When gender dysphoria continues to exist when physical changes of puberty start (Tanner stage 2-3), medical care (next to the psychological care) is possible. In the late 1990s treatment with PS (using gonadotropin-releasing hormone analogues (GnRHa)) was introduced by clinicians in the Netherlands (Cohen-Kettenis, Delemarre-van de Waal & Gooren, 2008). Two established international transgender guidelines now recommend this treatment for adolescents who meet the diagnostic criteria for gender dysphoria, and fulfil the criteria for treatment with PS after they first exhibit physical changes of puberty 2 Social transition is the process by which individuals start living according to the gender role that matches their gender identity, for example by adopting a name, pronouns, and gender expression, such as haircuts and clothing which matches their gender identity.