Abstract Study question What are the current attitudes in Flemish adolescents aged 15-19 towards having children? Summary answer While the majority of adolescents want to have children, 25% have ambiguous feelings about having children and 10% indicate a wish to remain childless. What is known already In the past decades, a very positive attitude towards having children has been reported in young people. In the adult population, most people desire to have children or are already parents, but the group of people who choose to remain childfree is increasingly visible and vocal. The current generation of adolescents is more concerned about environmental impacts than previous generations. Study design, size, duration An anonymous online survey of multiple choice and open-ended questions was offered to adolescents in Flanders (Belgium). Forty – four schools in Flanders participated and 1700 adolescents completed the questionnaire from February 2022 to June 2022. We performed a qualitative analysis of answers in open ended questions. Participants/materials, setting, methods Adolescents aged 15 – 19 years old, attending the last two years of secondary school in Flanders (Belgium). Most pupils had the opportunity to complete the questionnaire during class, others chose to complete the questionnaire in their own free time. Main results and the role of chance The majority of pupils would like to have children (60.2%), a considerable proportion is still undecided (24.7%) and 10.8% report they do not want children. Significantly more boys than girls would like to have children (67% versus 61.7%, p < 0.01). Having a positive representation of children and the desire to build a family in the future are the most important reasons for wanting children. Adolescents who have ambiguous feelings or who do not want children are rather pragmatic in their decision-making. They may consider factors such as financial stability, career goals and personal development before deciding to have children. Other reasons for having an ...