Blood type and postpartum hemorrhage by mode of delivery: A retrospective cohort study.

Objective: To assess the relationship between postpartum hemorrhage and ABO blood type for vaginal delivery and cesarean delivery.

Study Design: This is a retrospective cohort study of data abstracted from the PeriBank database regarding demographics and delivery outcomes. All live singleton deliveries from January 2011 until March 2018 were included in this study.