1. Department of Anesthesia and Intensive Care, Unit of Obstetric Anesthesia, IRCCS Policlinic San Matteo Hospital Foundation, Pavia, Italy;
2. Clinical Epidemiology and Biostatistics, Scientific Direction, IRCCS Policlinic San Matteo Hospital Foundation, Pavia, Italy;
3. Department of Anesthesia and Intensive Care, ASST Lecco, Presidio Ospedaliero “S.L. Mandic”, Merate, Italy;
4. Department of Anesthesia and Intensive Care, Policlinic Tor Vergata, Roma, Italy;
5. Department of Obstetrics and Gynecology, IRCCS Policlinic San Matteo Hospital Foundation, Pavia, Italy