186 Chapter 10 Furthermore, even though age is often considered to be the best determinant for having MDC, the results of this study did not show a relation between age and level of MDC regarding starting PS (Dorn et al., 1995; Vrouenraets et al., 2021). One remark in this context is that the sample included few participants aged younger than 12, although research in other medical contexts shows that children under the age of 11 were not always deemed to be competent to consent (Hein et al., 2014; Vrouenraets et al., 2021). The study revealed that, in line with the expectations of the transgender adolescents, their parents, and the clinicians, and other studies, minors with a higher intelligence were assessed as better decision-making competent (Hein et al., 2015c; Miller et al., 2014; Vrouenraets et al., 2021; Vrouenraets et al., 2022a). Sex (birth-assigned girls) was also related to MDC in this sample. A hypothesis for the association between sex and MDC found in our study is that the birth-assigned girls participating in our study might have had a more advanced puberty compared with the participating birth-assigned boys, which might be related to a better understanding of the treatment’s consequences (Koerselman & Pekkarinen, 2017). This would be in line with the thoughts of the transgender adolescents, their parents, and the clinicians that developmental stage is related to MDC. Finally, psychological difficulties seemed to be of little relevance for MDC in our sample as we did not find an association between MDC and the duration of the adolescent’s diagnostic trajectory, and behavioural and/or emotional difficulties (Vrouenraets et al., 2021). 2. CONSIDERATIONS REGARDING STARTING OR REFRAINING FROM PUBERTY SUPPRESSION The current state of science regarding the medical aspects of care for transgender minors is promising. Several review studies show reassuring results regarding the use of PS (e.g. Ramos et al., 2021; Rew et al., 2021; Turban & Ehrensaft, 2018). Even though PS may have an effect on bone mineral density, results show that kidney function, liver function, and liver profiles seem to be unaffected (Marantz & Coates, 1991; Schagen et al., 2016; Steensma et al., 2013). Due to these effects of PS, the established international transgender guidelines recommend careful monitoring of the minors’ physical development while receiving PS, by means of, among others, bone density assessments and blood monitoring, to ensure that testosterone and oestrogen are adequately suppressed (Coleman et al., 2022; Hembree et al., 2017; Klink et al., 2015; Vlot et al., 2017). Furthermore, even though concerns are raised about a decreased height velocity of the minors receiving PS, multiple studies show that although growth decelerated while minors received PS, there is an acceleration in growth while they subsequently received gender-affirming hormones (GAH) (e.g. Boogers et al., 2022; Korkmaz et al., 2019; Willemsen et al., 2022). Results show that adult height is not negatively affected by PS and GAH in transboys (Willemsen et al., 2022). The study of