102 Chapter 5 ethics support, as highly valuable in dealing with moral challenges in their clinical practice (Molewijk et al., 2008a; Vrouenraets, Hartman, Hein, de Vries, de Vries, & Molewijk, 2020). Moral case deliberation could also be used by the transgender treatment teams when, in clinical practice, they are confronted with moral challenges regarding adolescents’ MDC to start PS and/or its assessment. Aspects that are considered when assessing the adolescent’s medical decision-making competence Results further showed that the adolescents, parents, and clinicians mentioned several (contextual) aspects that, according to them, should be considered when assessing the adolescent’s MDC to start PS. One aspect various adolescents, parents, and clinicians mentioned with regard to this, was the understanding of the treatment and its consequences. Various adolescents, both continuers and discontinuers, mentioned that before they started PS, they were not aware of some of the psychosocial consequences of delaying puberty while their peers underwent multifaceted developmental accomplishments. An example of a potentially negative consequence of keeping the adolescent in a prepubertal state is isolating the adolescent from peers (Rosenthal, 2014). On the other hand, research shows that the adolescents’ psychological functioning improved or did not change after starting specialized transgender care involving PS (van der Miesen et al., 2020; Carmichael et al., 2021; Rew, Young, Monge, & Bogucka, 2021). Only a few of the adolescents and their parents stated that they fully understood what PS and its consequences entailed, but even so, the adolescents found themselves able to decide about whether or not to start the treatment. In both the beforementioned quantitative study regarding the assessment of MDC in transgender adolescents and the current qualitative study, the adolescents are judged competent and find themselves competent to decide on starting PS (Vrouenraets et al., 2021). Seemingly, fully understanding and appreciating the treatment are not requirements for MDC to start PS. This is in line with the statements of some clinicians and parents that not being able to understand and appreciate the impact of certain consequences of PS is inherent to the age, developmental stage and/or life experience of the adolescent, just as previous research in other contexts has shown (Hein et al., 2015b). Age was another factor that most participants mentioned that may have a decisive impact on MDC, and should therefore be considered when assessing the adolescents’ MDC. Age is often considered to be the best indicator of MDC (Hein et al., 2015c). Research shows that children aged ≥ 12 years may have MDC, provided they have favourable environmental factors (Grootens-Wiegers, Hein, van den Broek, & de Vries, 2017; Hein et al., 2014). On the other hand, the same research shows that there is no universal agreement regarding the age at which children can reasonably be expected to have MDC regarding every decision in every context. Early development of the reward system of the brain in combination with