Materials and Methods
We performed a retrospective cohort study, which included all live, vertex, term vaginal deliveries (defined as 37-42 weeks of gestation) in a single large tertiary center between January 2006 and December 2018. We excluded stillbirths, cesarean deliveries (CD), vacuum assisted vaginal deliveries (VAVD), multifetal gestations, home deliveries, non-vertex deliveries, vaginal deliveries following more than two previous CD and deliveries by non- CNMs.
Anonymized patient data were extracted from the real time electronic computerized medical record (EMR) that is continuously updated during labor and delivery by certified midwives and obstetricians. Trained medical secretaries further validate the data before it is entered into the database. The EMR includes demographic characteristics, medical and obstetrical history, and data regarding the course of labor and delivery.