Comparative Study of Effects of Low Dose Bupivacaine Only Versus Bupivacaine, Fentanyl and Bupivacaine, Fentanyl and Morphine on Subarachnoid Block for Labour Analgesia

Abstract

Background: Labour pain management remains inadequate in many low-resource settings despite the proven effectiveness of neuraxial analgesia. Single-shot spinal (SSS) analgesia offers a simple and cost-effective option for labour pain relief. Objective: To compare the efficacy and safety of three SSS analgesic regimens in parturients during active labour. Methods: This prospective, randomised, double-blind study enrolled 102 ASA II parturients aged 18–45 years in active labour (cervical dilatation ≥5 cm). Participants were randomly assigned to one of three groups: bupivacaine only (BO), bupivacaine plus fentanyl (BF), or bupivacaine plus fentanyl and morphine (BFM). The primary outcomes were the duration of analgesia and the time to the first request for additional analgesia. Secondary outcomes included pain scores, maternal satisfaction, maternal and foetal side effects, Apgar scores, and umbilical cord blood pH. Data were analysed using SPSS version 25, with statistical significance set at p ≤ 0.05. Results: Age-group distribution and mean weight did not differ significantly among the groups, whereas mean height and BMI differed significantly (p = 0.010 and p = 0.023, respectively). The mean duration of analgesia was significantly longer in the BFM group (239.35 ± 27.29 min) than in the BF (146.78 ± 12.19 min) and BO (119.41 ± 15.65 min) groups (p = 0.0001). Pain-category distributions differed significantly among the groups at 60 minutes (p = 0.016), 2 hours (p = 0.001), and 3 hours (p = 0.001), but not at 4 hours (p = 0.858). Patient satisfaction was highest in the BFM group, in which all participants reported satisfaction (100%; p = 0.001). Nausea and vomiting occurred more frequently in the BO group at the later assessment intervals. Apgar scores did not differ significantly at 1 minute (p = 0.590) but differed at 5 minutes (p = 0.031); umbilical cord blood pH differed among the groups at both 1 and 5 minutes (p = 0.001 and p = 0.024, respectively). Conclusion: The addition of fentanyl and low-dose morphine to intrathecal bupivacaine was associated with longer-lasting labour analgesia and greater maternal satisfaction than bupivacaine alone or the bupivacaine–fentanyl combination, with the reported maternal and foetal outcomes requiring interpretation alongside the study data.