Maternal risk factors for peripartum transfusion

Background: Postpartum hemorrhage remains one of the most significant maternal complications of childbirth in the United States, with peripartum transfusion the most commonly identified morbidity. Methods: 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. Results: 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) 9.5-10.5g/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. Conclusions: 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.