Blood transfusion in contemporary obstetric practice.

Blood transfusion during or after delivery is a serious and sometimes predictable event. An analysis of 30,621 consecutive deliveries showed that previous abortion, bleeding during pregnancy, polyhydramnios, oligohydramnios, operative delivery, multiple pregnancy, abnormal placentation, and primary cesarean were each associated with unexpectedly high transfusion rates. Most women who were transfused received 2 U of blood or fewer. Only 0.09% of pregnant women received more than 8 U. There has been a temporal reduction in the rate of blood transfusion in obstetric practice over the past 10 years. Currently, it appears that approximately 2% of women may require blood transfusion during the peripartum period.