Ethics approval and consent to participate
The study has been approved by the Regional Swedish Research Ethical Review Board at Uppsala the 5th of April 2017 (diary number 2017/009) and has been performed in accordance with the Declaration of Helsinki. Participation in the study was voluntary and the parents could withdraw at any time without any explanation. They received oral and written information about study goals and design and had the opportunity to ask questions to the study coordinator as well as the researchers before they consented to participate. Primary data were stored in a protected file area before, during and after the analysis. The randomized trial was registered retrospectively in the ISRCTN registry, study record 14429952 10.1186/ISRCTN14429952)