11 General introduction 1 present to a lesser or greater extent, and that it may fluctuate over time. Furthermore, the authors aimed to make a move to depsychopathologization of the condition. They wanted the terminology to be non-stigmatizing and acceptable to those who fulfil the criteria (Cohen-Kettenis & Pfafflin, 2010; Rodríguez, Granda, & González, 2018). Whereas the DSM is a psychiatric classification system, in the ICD-11, the classification gender incongruence was moved from the chapter ‘mental disorder’ to a new chapter entitled ‘conditions related to sexual health’. The reason for this was to avoid the mental health stigma of being diagnosed with a mental disorder (World Health Organization, 2022). Since the terms used to address this condition changed over time, and during the undertaking of this research, in this thesis several terms will be used alternating1. In the general introduction, and in the general discussion the term ‘transgender children/adolescents/individuals’ is used as an umbrella term to refer to individuals who have gender incongruent experiences and/ or present with questions about their gender identity, and to individuals diagnosed with gender dysphoria. Until a couple of years ago, gender dysphoria was considered to occur rarely (Zucker & Lawrence, 2009). Over the past decades however, the number of minors seeking care regarding their gender incongruent experiences has increased tremendously throughout the Western world (Aitken et al., 2015; Chen, Fuqua, & Eugster, 2016; Pang et al., 2020; de Vries & Cohen-Kettenis, 2012; Wood et al., 2013; Handler et al., 2019). For example, by 2017, the annual number of referrals in Norway, the UK and Sweden had increased 12-, 14-, and 19-fold respectively compared to 2011 (Kaltiala et al., 2020). Finland is another example of a country with an immense increase of child and adolescent referrals. In Finland, the annual number of referrals in 2017 had increased six-fold compared to 2011, when the first two gender identity clinics for children and adolescents were introduced in this country (Kaltiala-Heino, Sumia, Työläjärvi, & Lindberg, 2015). Similarly, in the Netherlands, there was an immense increase in the number of adolescents assessed at gender identity clinics between 2000 and 2016 (Arnoldussen et al. 2020; Arnoldussen et al., 2022b). 1 Terms that will be used in the chapters 2 to 7 are ‘transgender minors/children/adolescents/ people/individuals’, ‘adolescents diagnosed with gender dysphoria’, and ‘identifying as transgender’. In some chapters terms are used that we would not use nowadays anymore; terms like ‘gender dysphoric minors/adolescents/adults’, and ‘children/adolescents/individuals with gender dysphoria’. The reason for this is that, even though in many health care systems a diagnosis of gender dysphoria is used for giving access to state funded transgender health care, using these terms does reify the condition (Bouman et al., 2017). Furthermore, chapter 4 contains the following sentence: ‘This article uses the term ‘transgender adults/adolescents/children’ to refer to persons diagnosed with gender dysphoria’. We would not use this sentence nowadays anymore, since the term ‘transgender adults/adolescents/children’ is used as an umbrella term, and may also be used for individuals who do not (yet) have a gender dysphoria diagnosis, but nevertheless have gender incongruent experiences and/or questions about their gender identity.