Ethics approval
This study used routinely collected administrative hospital data collected in the Certificato di assistenza al parto (CeDAP). CeDAP is mandatory by law and is run by the Regional Health Systems which can use personal data without individual consent to evaluate service provision and performance. (Italian Ministry of Health. Decree July 16, 2001. [https://www.gazzettaufficiale.it/eli/id/2001/09/19/001G0405/sg]