Funding for this research was provided by:
European Social Fund
European Regional Development Fund
Text and Data Mining valid from 2018-04-27
Received: 27 June 2017
Accepted: 20 April 2018
First Online: 27 April 2018
Ethics approval and consent to participate
: The study was designed under the supervision of the Ethics Committee of the University of Leipzig, and this committee also granted ethics approval for the study (Reg. No. 264-10-19042010). All participants were informed about the study program and the long-term use of data. Informed written consent was obtained from parents of all participants, irrespective of age until age 18 years. For children 12 years old or older, informed written consent was additionally obtained from children themselves.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.