Use of Labor Neuraxial Analgesia for Vaginal Delivery and Severe Maternal Morbidity

IMPORTANCE: Addressing severe maternal morbidity (SMM) is a public health priority in the US. Use of labor neuraxial analgesia for vaginal delivery is suggested to reduce the risk of postpartum hemorrhage (PPH), the leading cause of preventable severe maternal morbidity. OBJECTIVE: To assess the association between the use of labor neuraxial analgesia for vaginal delivery and SMM. DESIGN, SETTING, AND PARTICIPANTS: In this population-based cross-sectional study, women aged 15 to 49 years undergoing their first vaginal delivery were included. Data were taken from hospital discharge records from New York between January 2010 and December 2017. Data were analyzed from November 2020 to November 2021. EXPOSURES: Neuraxial analgesia (ie, epidural or combined spinal-epidural) vs no neuraxial analgesia. MAIN OUTCOMES AND MEASURES: The primary outcome was SMM, as defined by the US Centers for Disease Control and Prevention, and the secondary outcome was PPH. Adjusted odds ratios (aORs) and 95% CIs of SMM associated with neuraxial analgesia were estimated using the inverse propensity score–weighting method and stratified according to race and ethnicity (non-Hispanic White vs racial and ethnic minority women, including non-Hispanic Asian or Pacific Islander, non-Hispanic Black, Hispanic, and other race and ethnicity) and to the comorbidity index for obstetric patients (low-risk vs high-risk women). The proportion of the association of neuraxial analgesia with the risk of SMM mediated through PPH was estimated using mediation analysis. RESULTS: Of 575 524 included women, the mean (SD) age was 28 (6) years, and 46 065 (8.0%) were non-Hispanic Asian or Pacific Islander, 88 577 (15.4%) were non-Hispanic Black, 104 866 (18.2%) were Hispanic, 258 276 (44.9%) were non-Hispanic White, and 74 534 (13.0%) were other race and ethnicity. A total of 400 346 women (69.6%) were in the low-risk group and 175 178 (30.4%) in the high-risk group, and 272 921 women (47.4%) received neuraxial analgesia. SMM occurred in 7712 women (1.3%), of which 2748 (35.6%) had PPH. Before weighting, the incidence of SMM was 1.3% (3486 of 272 291) with neuraxial analgesia compared with 1.4% (4226 of 302 603) without neuraxial analgesia (risk difference, −0.12 per 100; 95% CI, −0.17 to −0.07). After weighting, the aOR of SMM associated with neuraxial analgesia was 0.86 (95% CI, 0.82-0.90). Decreased risk of SMM associated with neuraxial analgesia was similar between non-Hispanic White women and racial and ethnic minority women and between low-risk and high-risk women. More than one-fifth (21%; 95% CI, 14-28) of the observed association of neuraxial analgesia with the risk of SMM was mediated through the decreased risk of PPH. CONCLUSIONS AND RELEVANCE: Findings from this study suggest that use of neuraxial analgesia for vaginal delivery is associated with a 14% decrease in the risk of SMM. Increasing access to and utilization of labor neuraxial analgesia may contribute to improving maternal health outcomes.