Study design, participants
For this retrospective register study, primiparous parturients with spontaneous vaginal delivery at term (gestation week ≥37+0) were included and divided into two groups depending on their EA status (yes/no). Multiple pregnancies were excluded. These criteria were applied to keep the study population as homogenous as possible, because the National Birth Registry contains limited information on the medical condition of each individual. Antepartum intrauterine foetal demise (IUFD) were excluded for analysis of primary and secondary objectives. No parturients or patients were involved in the planning and design of the study. Hospitals were divided into four categories: (1) hospitals with less than 500 deliveries per year, (2) hospitals with >500 deliveries per year, (3) Perinatalcentre 2, defined as specialised centre for obstetric cases with paediatric in-house services for 24 hours, (4) Perinatalcentre 1, defined as specialised centre for complex obstetric cases with paediatric in-house services for 24 hours including a neonatological intensive care unit, a paediatric surgery department and radiology particularly trained for foetal diagnostic.