The goal of this observational cohort study is to identify and predict parameters for successful testicular sperm extraction (TESE) procedures or semen cryopreservation more accurately and to evaluate the decision making process and the experience of postponing or temporarily discontinuing puberty suppression to undergo successful fertility preservation. in transfeminine (assigned male at birth) adolescents. The main question[s] it aims to answer are:

• What is the optimal timing for fertility preservation before the start or after temporarily discontinuing puberty suppression puberty suppression
• How do transfeminine adolescents and their parents experience the decision making process of fertility preservation
• how do transfeminine adolescents and their parents experienced postponing or temporarily discontinuing puberty suppression to undergo successful fertility preservation?

Participants will be asked to use their medical data, answer a questionnaire or participate in a (online) interview.

Inclusion Criteria:

• Before start of puberty suppresion with a wish for fertility preservation
• After discontinuing puberty suppersion before the start of hormone therapy

Exclusion Criteria:

• Tanner stage > 4/5

assigned male at birth with a gender diverse gender identity

assigned male at birth adolescents with gender dysphoria who wish fertilty preservation before the start of puberty suppression.