113 Trajectories of adolescents treated with gonadotropin‑releasing hormone analogues for gender dysphoria 6 2019a; Richards et al., 2019; Stein, 2012; Vrouenraets et al., 2015). It is unknown if the use of GnRHa prevents resolution of gender dysphoria (Korte et al., 2008). Many prepubertal children with gender dysphoria no longer experience gender dysphoria in adolescence, and the experience of romantic and sexual attraction is thought to play an important role in this process (Steensma, Biemond, de Boer, & Cohen-Kettenis, 2011). Some may come to understand themselves as homosexual or bisexual (Steensma et al., 2011). GnRHa, by suppressing sexual development, might interfere with this process (Korte et al., 2008). Another concern is that although treatment with GnRHa is to be used as an extended diagnostic phase, the start of it may lead the adolescents and parents to assume that transgender outcome is the only possible outcome which may prevent exploration of other possibilities (Leibowitz & de Vries, 2016). To gain more insight into the use of GnRHa in adolescents with gender dysphoria, the current study aims to document trajectories after the initiation of GnRHa, i.e., discontinuation of GnRHa, prolonged use of GnRHa, and initiation of GAH; to investigate the duration of treatment with GnRHa; and to explore reasons for extended use and discontinuation of GnRHa. METHOD Participants This is a single-centre retrospective study. Out of 269 children and adolescents registered at the Curium-Leiden University Medical Centre gender identity clinic in Leiden, the Netherlands, 214 were pubertal and within the appropriate age range for treatment at our paediatric clinic. Out of these, 143 (67%) had started treatment with GnRHa between November 2010 (when the clinic first started) and January 1, 2018. The study population consisted of these 143 adolescents (38 transgirls, 105 transboys). Not included in the study were children and adolescents in whom gender dysphoria was not diagnosed (n = 39), those who had coexisting problems that interfered with the diagnostic process and/ or might interfere with successful treatment (n = 9), those that did not wish hormonal treatment (n = 4 ), those in whom the diagnostic evaluation was still ongoing (n = 10), and those who had stopped to attend appointments (n = 9). Of adolescents who had started GnRHa, treatment status as of 1 July 2019 was reviewed. If they had used GnRHa monotherapy for more than three months longer than minimally required before the start of GAH according to the local protocol (see below for description of the treatment protocol), the reason for this was noted. The three months was chosen to select those who may have had a prolonged diagnostic phase rather than those in whom treatment with GAH started slightly later due to logistical issues such as rescheduling of