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Article History

Received: 9 December 2019

Accepted: 18 October 2020

First Online: 4 November 2020

Change Date: 19 April 2024

Change Type: Correction

Change Details: This article has been retracted. Please see the Retraction Notice for more detail:

Change Details: https://doi.org/10.1186/s12889-024-18629-0

Ethics approval and consent to participate

: The Regional Committee for Medical & Health Research Ethics found the research project to be outside the remit of the Act on Medical and Health Research; therefore, the study could be implemented without its approval (ref no. 2015/1034). Approval from the Norwegian centre for research data was given because no personal or sensitive information was collected or stored (ref no. 44760/3). Written consent was obtained from all parents based on both oral and written information about the project.

: Not applicable.

: The authors have no conflict of interest to disclose.