Risk factors for early postpartum hemorrhage: A retrospective, population-based, cohort analysis

Objective: To identify risk factors for developing early postpartum hemorrhage (PPH) and to examine whether risk factors vary according to severity and mode of delivery. Methods: A population-based cohort study was conducted in which all deliveries at a tertiary medical center were included. Risk factors for developing early PPH were compared based on the severity of bleeding as well as the mode of delivery. Multiple logistic regression models were used to control for confounders. Results: Among 322 497 deliveries included in the analysis, early PPH complicated 1811 (0.56%) of all deliveries. Among all cases of early PPH, 505 deliveries (28%) were complicated with severe PPH. Using a logistic regression model, in vitro fertilization (IVF) pregnancy, previous cesarean delivery (CD), pre-eclampsia, placental abruption, and uterine rupture were independently associated only with severe early PPH, while non-progressive second stage of labor, induction of labor, and large for gestational age were independently associated with both severe and mild early PPH. When applying an additional logistic regression model, whereas IVF pregnancy, pre-eclampsia, and large for gestational age were independently associated with early PPH among vaginal deliveries only, placenta previa was independently associated with early PPH among CD only. Conclusions: Independent risk factors for developing severe PPH solely include IVF pregnancy, previous CD, pre-eclampsia, placental abruption, and uterine rupture. IVF pregnancy, pre-eclampsia, and large for gestational age are independent risk factors for early PPH following vaginal delivery, while placenta previa is independently associated with early PPH after CD only. Due to the recognition of the importance of both the provider and institutional planning and preparation for PPH, the study's results should be viewed within the scope of its retrospective cohort design.