1. Department of Clinical Sciences and Community Health University of Milan Milan Italy
2. Department of Obstetrics, Gynecology and Neonatology Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Milan Italy
3. Unit of Biostatistics, Epidemiology and Public Health, Department of Statistics and Quantitative Methods University of Milano‐Bicocca Milan Italy
4. National Center for Healthcare Research and Pharmacoepidemiology Milan Italy