91 Medical decision‑making competence regarding puberty suppression: perceptions of transgender adolescents, their parents and clinicians 5 In addition, some clinicians mentioned that sometimes an adolescent may not have MDC regarding a specific part or consequence of the treatment. “In that case the adolescent does not have medical decision-making competence regarding that aspect [the ability to decide about possible loss of fertility] [...] that [medical decision-making competence] develops much later in this area. […] And are you then going to postpone the start of treatment in the meantime [until the adolescent has medical decision-making competence regarding this aspect]? That’s pretty complicated.” - Focus group with clinicians Furthermore, the clinicians stated that in their daily practice, MDC is generally assessed implicitly and not in a structured way. “We [as clinicians] have not quite formalized it [the assessment ofmedical decision-making competence] as some kind of medical decision-making competence measurement. Nevertheless, of course you do it [assess one’s medical decision-making competence]; you look at what exactly did the person tell me, what were his/her thoughts about it, and what can he/she tell me about the idea of how it [life after the start with puberty suppression] will go forward. And as a matter of fact, that also includes an assessment of the extent to which this person can understand and appreciate it [starting treatment with puberty suppression and its consequences].” - Focus group with clinicians Aspects that are considered when assessing the adolescent’s medical decision-making competence The adolescents, their parents and clinicians described several aspects they take into account when assessing MDC to start PS. From the interviews and the focus groups, three subtopics emerged. Understanding and appreciating what the treatment and its (long-term) consequences entail, and making the decision deliberately The informants stated that understanding relevant information regarding the treatment is necessary for MDC. Nevertheless, only a few adolescents and their parents stated that the adolescent fully understood what PS entailed before starting the treatment. Some adolescents mentioned that they were able to understand most of what the treatment entailed. “You receive so much explanation about it [the treatment with puberty suppression and its (possible) consequences] and you also have to fill in several forms. So you really know what it entails.” - Interview with a transgirl who continued PS; age at start PS: 12.9; age at interview: 17.8