1. Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, Stockholm, Sweden
2. European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
3. University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Pisa, Italy
4. Health Directorate, Office de la Naissance et de l'Enfance, Brussels, Belgium
5. University of Salento, Department of Biological and Environmental Science and Technology, Lecce, Italy