Magnesium sulfate reduces postoperative pain in women with cesarean section: A meta-analysis of randomized controlled trials.

OBJECTIVES The use of magnesium sulfate (MgSO4 ) as an adjunct in different anesthetic regimens for cesarean section (CS) delivery often reports conflicting results. This study aimed to review the effectiveness of MgSO4 on improving postoperative analgesia after CS systematically. METHODS PubMed, Embase, and the Cochrane library were searched for randomized controlled trials (RCTs) published from inception to February 2020. RESULTS A total of 880 women were included (440 in each group). MgSO4 had a statistically significant effect compared to the control group on the highest VAS (weighted mean difference [WMD] = -0.74, 95% confidence interval [CI] = -1.03 to -0.46, p < 0.001, I2  = 91.7%, pheterogeneity  < 0.001) and the last VAS (WMD = -0.47, 95% CI = -0.71 to -0.23, p < 0.001, I2  = 95.0%, pheterogeneity  < 0.001). MgSO4 prolonged the time to the first use of analgesia compared to the control group (standardized mean difference [SMD] = -3.03 min, 95% CI = -4.32 to -1.74, p < 0.001, I2  = 96.3%, pheterogeneity  < 0.001). MgSO4 decreased the consumption of analgesia compared to the control group (SMD = -3.20 mg of IV morphine equivalent, 95% CI: -5.45 to -0.95, p = 0.005, I2  = 97.6%, pheterogeneity  < 0.001). DISCUSSION MgSO4 decreases the highest VAS in women who underwent general anesthesia, spinal anesthesia, or epidural for CS (all p < 0.05). Additional MgSO4 significantly reduces postoperative pain in women undergoing CS.