1. School of Medicine and Surgery, University of Milano Bicocca, 20900 Monza, Italy
2. Department of Obstetrics, Foundation IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
3. Maternal and Child Committee, Lombardy Region, 20124 Milan, Italy
4. ARIA, 20124 Milan, Italy
5. Welfare Department, Epidemiologic Observatory, Lombardy Region, 20124 Milan, Italy