[1] Univ Milan, Fdn IRCCS Ca Granda Osped Maggiore Policlin, Dept Clin Sci & Community Hlth, Neonatal Intens Care Unit, Via Commenda 12, I-20122 Milan, Italy
[2] Univ Roma La Sapienza, Dept Pediat & Child Neuropsychiat, Neonatal Intens Care Unit, Viale Policlin 155, I-00161 Rome, Italy
[3] Univ Milan, Fdn IRCCS Ca Granda Osped Maggiore Policlin, Dept Prevent Med, Epidemiol Unit, Via Commenda 12, I-20122 Milan, Italy