1. Faculty of Medicine, Universidade do Porto, Porto, Portugal;
2. Department of Community Medicine, Information and Health Decision Sciences (MEDCIDS), Faculty of Medicine, Universidade do Porto, Porto, Portugal;
3. Center for Health Technology and Services Research (CINTESIS), Porto, Portugal;
4. Neonatal Intensive Care Unit, Centro Hospitalar São João, Porto, Portugal;
5. Department of Pediatrics, Faculty of Medicine, Universidade do Porto, Porto, Portugal;
6. Department of Pediatrics, Centro Hospitalar São João, Porto, Portugal;
7. EpiUnit, Institute of Public Health, Universidade do Porto, Porto, Portugal