Funding for this research was provided by:
Global Geo Health Data Centre from Utrecht University
Received: 21 December 2018
Accepted: 26 April 2019
First Online: 16 May 2019
Ethics approval and consent to participate
: Written informed consent is obtained from all parents. The paediatric medical ethics committee of the University Medical Centre Utrecht has approved the protocol.
: Not applicable.
: The authors declare that they have no actual or potential competing financial interests.
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