Commentary

In 1995, the Eclampsia trial¹ showed that magnesium sulphate was superior to diazepam or phenytoin in reducing the prevalence of recurrent eclamptic seizures. This group of investigations and collaborators has now logically moved from treatment to prevention of the primary eclamptic episode. The MAGPIE trial showed that magnesium sulphate was effective regardless of severity of pre-eclampsia, gestational age at trial entry, or whether delivery had occurred. In the Magpie trial and the earlier Eclampsia trial, maternal mortality was reduced but failed to reach statistical significance; however, future meta-analysis will improve power in this regard. Neither study showed any effect on perinatal mortality.

Magnesium sulphate was not effective in reducing the eclamptic rate in countries with a low perinatal mortality rate. It must be noted, however, that less severe cases were involved in these countries and the sample size was small.

The safety of magnesium sulphate at the trial doses is now beyond dispute having been given in several healthcare situations to thousands of participants. Given its safety, effectiveness, and low cost, it is imperative that a concerted effort be made to educate healthcare workers and to make this intervention available to every facility caring for pregnant women. In areas where magnesium sulphate is already used extensively, investigators might want to adjust dosing schedules or run trials to determine if a different dose brings more benefit. One major question concerns the inclusion of participants receiving anticonvulsive interventions before randomisation (approximately 9%). These interventions were, however, equally distributed between magnesium sulphate and placebo groups. Magnesium sulphate showed no effect in this group of patients when analysed separately, but this lack of difference may be a factor of sample size rather than noneffectiveness or dampening effect of the loading dose of magnesium sulphate.