1. Department of Neonatology; Hospital Universitario 12 de Octubre; Instituto de investigación Hospital 12 de octubre (i+12); Madrid Spain
2. Department of Neonatology; Hospital Universitario Severo Ochoa; Madrid Spain
3. Department of Neonatology; Hospital Universitario La Paz; Madrid Spain
4. Department of Pediatrics; Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM); Madrid Spain
5. Department of Neonatology; Hospital Universitario Getafe; Madrid Spain
6. Department for the Management and Human Nursing Resource Development; Hospital General Universitario Gregorio Marañón; Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM); Madrid Spain
7. Centro de Ciencias de la Salud San Rafael; Universidad Antonio de Nebrija Ciencias de la Salud; Madrid Spain
8. Department of Medicine and Surgery, Psychology; Preventive Medicine and Public Health and Immunology, and Medical Microbiology; Universidad Rey Juan Carlos; Madrid Spain