Postpartum hemorrhage remains one of the most significant maternal complications of childbirth in the United States, with peripartum transfusion the most commonly identified morbidity.We completed a retrospective cohort study of women delivering at 20+ weeks at a large regional obstetric hospital between 2000 and 2008. Data were extracted from the institutional data warehouse; women with a potential coagulopathy were excluded. The association of maternal and obstetric factors with odds of transfusion was explored using univariate and multivariable logistic regression.We identified 59,282 deliveries and 614 cases of transfusion, an incidence rate of 10.4/1,000 deliveries. Rates were highest for black (14.1/1,000 deliveries) and lowest for white (8.4/1,000 deliveries) women. Increased odds of perinatal transfusion were seen for women with anemia at entry to labor and delivery (odds ratio [OR] 3.03, 95% confidence interval [CI] 2.43-3.79 for hemoglobin (Hgb) 9.5-10.5 g/dL; OR 12.65, 95% CI 10.35-15.46 for Hgb<9.5 g/dL) and those undergoing a cesarean delivery (OR 4.28, 95% CI 3.62-5.05). The excess risk associated with black race was eliminated after adjusting for anemia and other covariates. A synergistic effect of anemia with delivery method was observed. Anemia was estimated to account for 31.7% of transfusions.Potentially modifiable factors most strongly associated with risk for transfusion were antenatal anemia and cesarean delivery, and their co-occurrence was synergistic. Anemia is an easily identified and treatable risk factor and warrants focus as part of preconception and interconception care in childbearing women.
