Evidence and practice: the magnesium sulphate story

There is now strong evidence from systematic reviews of randomised trials to support the use of magnesium sulphate for the prevention and treatment of eclampsia. Magnesium sulphate more than halves the risk of eclampsia for women with pre-eclampsia (relative risk (RR) 0.41, 95% confidence interval (CI) 0.29–0.58; number needed to treat (NNT) 102 (95% CI 72–173) compared to placebo. For treatment of eclampsia, magnesium sulphate lowers the risk of maternal death (RR 0.59, 95% CI 0.37–0.94) and of recurrence of further fits (RR 0.44, 95% CI 0.34–0.57) compared to diazepam. Magnesium sulphate also reduces the risk of further fits compared to phenytoin (RR 0.31, 95% CI 0.20–0.47) and to lytic cocktail (RR 0.09, 95% CI 0.03–0.24).