Risk factors for postpartum hemorrhage following cesarean delivery.

Objective: To identify risk factors for postpartum hemorrhage (PPH) following cesarean delivery (CD).
Methods: A retrospective study of all women who underwent CD in a university-affiliated tertiary hospital (2014-15). PPH was defined as any of the following: clinical PPH (≥1000 ml estimated blood loss), hemoglobin (Hb) drop ≥3 g/dl (the difference between pre-CD Hb level within a 24 h prior to the delivery) and post-CD (nadir level during the first 72 h after CD)) or the need for blood products transfusion. The characteristics of women with PPH following CD were compared to a control group of those with CD without PPH.
Results: Of the 15,564 deliveries during the study period, 3208 (20.6%) women met inclusion criteria, of them, 307 (9.6%) had PPH and 2901 (90.4%) served as controls. Women in the PPH group were younger (32.6 ± 5.3 vs. 33.5 ± 5.4, p  = .006) and more often nulliparous (45.9% vs. 33.3%, p <.001) compared to the controls. However, there were no differences between the groups regarding the rate of multiple gestations, maternal diabetes mellitus, hypertensive disorders, polyhydramnios, and macrosomia. The rates of induction of labor (16.3% vs. 8.6%, p <.001) and urgent CD (47.9% vs. 32.0%, p <.001) were higher in the PPH group compared to the controls. In multivariate logistic regression, predictors for PPH following CD were (odds ratio, 95% confidence interval) urgent CS (1.57, 1.78-2.11, p  = .002), CD duration (1.02, 1.01-1.03, p <.001), and the number of previous CDs (0.74, 0.62-0.90, p  = .003).
Conclusions: In women undergoing cesarean section, urgent CD, the duration of the surgery, and the number of the previous CD are associated with the risk of PPH and should be taken into consideration during the postpartum assessment.