15 General introduction 1 mastectomy, gonadectomy and/or hysterectomy, is recommended when the transgender individual and clinician(s) agree that this is medically necessary, and that it would be beneficial for the transgender individual’s overall well-being and/or health (Hembree et al., 2017). The Endocrine Society clinical practice guideline and the 7th version of the Standards of Care recommend deferring surgery until the individual is at least 18 years old (Coleman et al., 2012; Hembree et al., 2017). Only with regard to mastectomy, the 7th version of the Standards of Care describes that it could be carried out before the age of 18 (Coleman et al., 2012). Therefore, the age requirement for mastectomy in some countries is below 18. For example, in the Netherlands, the minimum age has been lowered in recent years, and is now 16. The recently published 8th version of the Standards of Care does not describe any age limits for gender-affirming surgery (Coleman et al., 2022). PUBERTY SUPPRESSION The two established international transgender clinical guidelines outline several reasons for using PS in the early stages of puberty of transgender adolescents, which largely correspond to the reasons given in the late 1990s, when this treatment was first introduced in the Netherlands (Cohen-Kettenis et al., 2008; Coleman et al., 2022; Hembree et al., 2017). One of the reasons is that PS suppresses (further) development of secondary sex characteristics in a reversible manner (Hembree et al., 2017). It is therefore applied to extend the exploration and assessment phase. It provides the adolescents ‘extra’ time to make a balanced decision regarding subsequent GAMT by means of treatment with GAH, and possibly undergoing gender-affirming surgery, while creating peace of mind by relieving the adolescent’s suffering caused by the development of secondary sex characteristics (Cohen-Kettenis & van Goozen, 1998). Another important reason to start PS in early puberty is that the physical outcome may be more satisfactory compared to no use or use of PS in later stages of puberty, because the masculinization or feminization of the body, which accompanies pubertal development, is suppressed (Cohen-Kettenis & van Goozen, 1997; Smith, van Goozen, Kuiper, & Cohen-Kettenis, 2005). Additionally, some surgeries such as mastectomy may not be necessary or less invasive (i.e. periareolar rather than inframammary approach) because development of secondary sex characteristics is prevented (van de Grift et al., 2020). Furthermore, PS can be used in adolescents in later stages of puberty to, among others, prevent facial hair growth in transgirls (assigned male at birth, with a female gender identity), and to stop menses in transboys (assigned female at birth, with a male gender identity) (Hembree et al., 2017). PS may therefore result in life-long advantages for adolescents (Cohen-Kettenis & van Goozen, 1997). Little is known about how PS is perceived by the transgender adolescents themselves and their parents. More knowledge about the motivation of these stakeholders to apply for PS