A History of Cesarean Birth as a Risk Factor for Postpartum Hemorrhage Even After Successful Planned Vaginal Birth.

Background: It is unclear if a history of cesarean birth (CB) is a risk factor for postpartum hemorrhage (PPH) even after a successful planned vaginal birth.

Methods: A historical retrospective cohort study from all deliveries (42,456) between 2004 and 2019. Inclusion criteria were as follows: (i) women with only one previous CB; (ii) liveborn cephalic singleton pregnancy and term spontaneous labor; (iii) successful planned vaginal birth; (iv) no operative vaginal delivery; and (v) no history of PPH.