Anemia and risk of transfusion after vaginal delivery

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A new analysis of electronic health record (HER) data suggests that identifying and treating anemia in women who present for vaginal delivery may help lower risk of postpartum anemia. The findings were presented at the American Society of Anesthesiologists annual meeting and published in Anesthesiology.

Methods
For the analysis, researchers extracted data from New York University’s HER on vaginal delivery in women at 28 weeks’ gestation or more from January 1, 2014 to June 30, 2018. Nearly 19,000 such births were recorded during that time. The goal of the study was to examine the effect of maternal anemia during the third trimester-defined as hemoglobin less than 11 g/dL-on postpartum hemorrhage, transfusion requirements, and length of hospital stay.

Data analyzed included laboratory results on admission to Labor and Delivery, use of oxytocin for induction and/or augmentation of labor, vacuum and forceps-assisted delivery, vaginal birth after cesarean, birth weight, gestational age, multiple gestation, parity, quality of blood loss at delivery, red blood cell (RBC) transfusion, and length of stay. The authors used stepwise multiple linear and logistic regression to assess the association between anemia on admission and need for RBC transfusion, quantified blood loss, and length of stay. Adjustments were made for potential confounders, based on previous studies and those with a P< 0.25 in the univariable analysis.

Results
Overall incidence of anemia in the study population was 5.7%. Odds of receiving an RBC transfusion were 5.4 times higher in women with anemia versus those without anemia (95% CI 3.6 to 8.2). An adjusted analysis of quantified blood loss showed that anemic women bled 26.2 mL more than those without anemia (beta coefficient 95% CI8.8 to 43.7, P= 0.003. The difference in length of stay between women with and without anemia was statistically but not clinically significant (median 2.4 and 2.3 days, respectively; P< 0.001).

Conclusion
Anemia at time of admission, as a proxy for anemia in the third trimester, was associated with an increased likelihood of transfusion in the immediate post-delivery period, the authors said. “By identifying patients with anemia, and implementing effective therapy prior to delivery,” they believe, “we may be able to lower patient risks, improve patient outcomes and achieve cost savings for healthcare systems.”