Funding for this research was provided by:
Fundação para a Ciência e a Tecnologia (PTDC/DTP-EPI/3306/2014, UID/DTP/04750/2013, IF/01060/2015)
European Commission (FP7-ENV-2013-603946)
European Regional Development Fund (NORTE-01-0145-FEDER-000003)
Received: 27 March 2019
Accepted: 2 September 2019
First Online: 11 September 2019
Ethics approval and consent to participate
: All the phases of the study complied with the Ethical Principles for Medical Research Involving Human Subjects expressed in the Declaration of Helsinki. The study was approved by the University of Porto Medical School/ Centro Hospitalar São João ethics committee and all parents or legal representative signed an informed consent according Helsinki.
: Not applicable
: The authors declare that they have no competing interests.