Placental abruption: assessing trends in risk factors over time

Purpose: To evaluate changes in the independent contribution of different risk factors for placental abruption over time. Methods: In this retrospective nested case–control study, trends of change in ORs for known risk factors for placental abruption occurring in three consecutive 8-year intervals were compared. A univariate assessment of factors associated with placental abruption and two multivariable logistic regression models were constructed to identify independent risk factors for placental abruption. Trends of change in the incidence and specific contribution of various risk factors were compared along the study time-period. Results: During the study period, 295,946 pregnancies met the inclusion criteria; of these, 2170 (0.73%) were complicated with placental abruption. Using logistic regression models, previous cesarean delivery, in vitro fertilization (IVF) pregnancy, hypertensive disorders, polyhydramnios, and inadequate prenatal care were recognized as independent risk factors for placental abruption. While the relative contribution of IVF pregnancy and polyhydramnios to the overall risk for abruption decreased over the course of the study, previous cesarean delivery became a stronger contributor for placental abruption. Conclusion: In our study, a change over time in the specific contribution of different risk factors for placental abruption has been demonstrated.