Trend Changes in the individual contribution of risk factors for postpartum hemorrhage over more than two decades

Objective: Postpartum hemorrhage is an obstetric emergency with a rising incidence. The aim of this study was to identify trends in the specific contribution of various risk factors for postpartum hemorrhage by observing their odds ratios throughout different time periods. Study design: In this population-based retrospective cohort study trends of change in odds ratios for known risk factors for postpartum hemorrhage occurring in three consecutive eight-year intervals between 1988 and 2014 were compared. Two multivariable logistic regression models were used in order to identify independent risk factors for postpartum hemorrhage in our population. Trends of various risk factors were compared along the time period of the study. Results: The incidence of postpartum hemorrhage increased from 0.5% to 1988 to 0.6%. Using logistic regression models, preeclampsia, vacuum extraction delivery, retained placenta, perineal or vaginal tears and delivery of a large for gestational age neonate were recognized as independent risk factors for postpartum hemorrhage. While the odds ratios for perineal or vaginal tears significantly increased, odds ratios for delivery of a large for gestational age neonate significantly decreased. Odds ratios for the other risk factors did not change significantly. Conclusion: In our study, not only did the rates of statistically significant risk factors for postpartum hemorrhage change during the study period, the specific contribution of each risk factor changed as well. Having a better understanding of these trends might augment our ability to predict this grave obstetric complication and improve maternal outcomes in the future.