1 National Centre for Epidemiology, Surveillance, and Health Promotion, Istituto Superiore di Sanità, Italian National Institute of Health, Rome, Italy. Electronic address: serena.donati@iss.it.
2 National Centre for Epidemiology, Surveillance, and Health Promotion, Istituto Superiore di Sanità, Italian National Institute of Health, Rome, Italy.
3 Centro di documentazione sulla salute perinatale e riproduttiva, Regione Emilia-Romagna, Bologna, Italy.