1. Department of Neonatology, Gemeinnützige Gesellschaft der Franziskanerinnen zu Olpe, Marien-Hospital, Bonn, Germany
2. Department of Neonatology, Charité–Universitätsmedizin Berlin, Berlin, Germany
3. Institute of Social Medicine, Epidemiology and Health Economics, Charité–Universitätsmedizin Berlin, Berlin, Germany