Labor neuraxial analgesia may reduce the odds of postpartum hemorrhage, the leading indication for maternal blood transfusion during childbirth. This study tested the hypothesis that labor neuraxial analgesia is associated with reduced odds of maternal blood transfusion overall.
US birth certificate data in Natality File of the National Vital Statistics System for all 50 states from 2015 to 2018 for vaginal and intrapartum cesarean deliveries were analyzed. The exposure was labor neuraxial analgesia. The primary outcome was maternal blood transfusion, recorded on the birth certificate, which has low sensitivity for this outcome. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) of blood transfusion associated with neuraxial analgesia were estimated using propensity-score matching. The aORs were estimated overall and according to delivery mode, and treatment effect compared between vaginal and intrapartum cesarean deliveries using an interaction term. Sensitivity analyses were performed using inverse propensity-score weighting and quantitative bias analysis for outcome misclassification.
Of the 12,503,042 deliveries analyzed, 9,479,291 (75.82%) were with neuraxial analgesia and 42,485 (0.34%) involved maternal blood transfusion. After propensity-score matching, the incidence of blood transfusion was 0.30% in women without neuraxial analgesia (7907 of 2,589,493) and 0.20% in women with neuraxial analgesia (5225 of 2,589,493), yielding an aOR of 0.87 (95% CI: 0.82, 0.91) overall. For intrapartum cesarean deliveries, the aOR was 0.55 (95% CI: 0.48, 0.64), and for vaginal deliveries 0.93 (95% CI: 0.88, 0.98; P-value for the interaction term <0.001). Results were consistent in the sensitivity analyses, although the quantitative bias analysis demonstrated wide variation in potential effect size point estimates.
Labor neuraxial analgesia may be associated with reduced odds of maternal blood transfusion in intrapartum cesarean deliveries and, to a lesser extent, vaginal deliveries. The specific effect size varies widely by delivery mode and is unclear given the poor sensitivity of the dataset for the maternal transfusion primary outcome.