83 Medical decision‑making competence regarding puberty suppression: perceptions of transgender adolescents, their parents and clinicians 5 RESULTS From the interviews and focus groups, 10 themes emerged regarding transgender adolescents’ MDC to start PS. These 10 themes can be merged into three main themes: (1) challenges when assessing MDC to start PS, (2) aspects that are considered when assessing the adolescent’s MDC, and (3) relevance of MDC. Representative quotations are presented to illustrate the themes identified. Challenges when assessing medical decision-making competence to start puberty suppression During the interviews and focus groups the informants mentioned several aspects that challenged the assessment of MDC to start PS. Six subtopics further emerged from the data. Understanding and appreciating consequences of puberty suppression Most adolescents and parents mentioned that certain aspects of (the impact of) the treatment simply cannot be understood and appreciated by adolescents below a certain age. “I think I had thought about it [starting treatment with puberty suppression or not starting this treatment] pretty well. But as a 12 or 13 year-old, you cannot really judge what it is all about. So I had thought about it [starting the treatment or not], but only as much as I was able to at the time [I decided to start with the treatment].” - Interview with a transgirl who continued PS; age at start PS: 12.9; age at interview: 17.8 “It does not really meanmuch to a 12 year-old when you’re talking about osteoporosis. She [my daughter] understood [what osteoporosis meant], but she thought ‘what does it matter’, we’ll see about that later.” - Interview with a parent of a transgirl who continued PS; age at start PS: 12.9; age at interview: 17.8 Some adolescents, both continuers and discontinuers, wondered whether they were able to understand and appreciate the consequence of possible loss of fertility if they were to proceed to GAH and possibly gonadectomy, and whether they were able to carefully consider the possibility to freeze sperm or store oocytes before they started the treatment with PS. Some adolescents stated that during the period they were treated with PS, they started to realise what the impact of some consequences could be. Worth mentioning is that one parent whose child froze sperm mentioned the impact which the process of fertility preservation had on her child and on herself, instead of the impact of the possible loss of fertility.