Trend in neuraxial morphine use and postoperative analgesia after cesarean delivery in Japan from 2005 to 2020

The increasing rate of cesarean deliveries warrants obstetric anesthesiologists to deliver high-quality post-cesarean delivery analgesia. The aim of this study was to evaluate the temporal trends in the use of neuraxial morphine for cesarean deliveries and to describe the current postoperative analgesia practices. A retrospective cohort study using nationwide health insurance claims databases was conducted from 2005 to 2020 in Japan. Pregnant women who had undergone cesarean deliveries were included. The annual rate of neuraxial morphine use was extracted and analyzed. Additionally, we explored the patient- and facility-level factors associated with neuraxial morphine use through a multilevel logistic regression analysis. The cohort included 65,208 cesarean delivery cases from 2275 institutions. The prevalence of neuraxial morphine use was 16.0% (95% confidence interval [CI], 15.8-16.3) in the overall cohort. Intrathecal morphine was used in 20.6% (95% CI, 20.2-21.0) of spinal anesthesia cases. The trend in neuraxial morphine use steadily increased from 2005 to 2020. The significant predictors of neuraxial morphine use included spinal anesthesia, recent surgery, large medical facilities, and academic hospitals. Variations in the utilization of postoperative analgesia were observed. Our study described the current trend of neuraxial morphine use and the variation in postoperative analgesia practice in Japan.