Objective: To determine whether delivery mode influences placental chorionic plate arterial and venous vascular reactivity. Methods: Normal term placentas were obtained after vaginal delivery or cesarean section. Chorionic plate arterial and venous function was assessed by wire myography. Results: Sodium nitroprusside-induced arterial relaxation increased post cesarean section at 20% oxygen. Decreased U46619-induced venous contraction was observed in vaginal deliveries at 7% oxygen. Sodium nitroprusside-induced relaxation increased in vaginal delivery at 20% oxygen. Conclusion: Delivery mode does not alter chorionic plate arterial vascular reactivity under physiological conditions, however venous reactivity was modified, a factor for consideration when interpreting functional experimental data. Copyright © Informa Healthcare.