Which of the following is the most important risk factor for abruptio placenta?

• A. Chronic maternal hypertension with superimposed preeclampsia
• B. History of abruption in a prior pregnancy
• C. Cigarette smoking
• D. Female age over 40

Answer: (B)

A prior placental abruption is the strongest single predictor of another abruption. If it happened before, the risk of recurrence in a future pregnancy is substantially higher—often cited around 10–25%—reflecting an underlying vulnerability of the uteroplacental interface or placental vasculature. The other factors—chronic hypertension with superimposed preeclampsia, cigarette smoking, and age over 40—do raise risk, but not as prominently as a previous abruption. So the history of an abruption in a prior pregnancy best explains why an abruptio placentae is more likely to occur again.