Best evidence in anesthetic practice: prevention: magnesium sulfate reduces the risk of eclampsia in women with pre-eclampsia.

Structured abstract Question: In women with pre-eclampsia, does peripartum administration of magnesium sulfate decrease the risk of eclampsia, maternal morbidity, or neonatal morbidity compared to placebo? Design: Multicentre, randomized, double-blind, placebo-controlled trial. Setting: One hundred and seventy-five secondary and tertiary level hospitals in 33 countries. Patients: Ten thousand one hundred and forty-one women who were pregnant or # 24 hr postpartum, with at least two blood pressure readings of $ 90 mmHg diastolic blood pressure or $ 140 mmHg systolic blood pressure, proteinuria of 1 + or more, and clinical uncertainty of the benefit of the use of magnesium sulfate. Exclusion criteria were hypersensitivity to magnesium, hepatic coma with risk of renal failure, or myasthenia gravis. Intervention: Five thousand and seventy-one women were allocated to magnesium 4 g iv (loading dose) followed by a maintenance regimen of either 1 g·hr–1 iv infusion for 24 hr or 2.5 to 5 g im every four hours for 24 hr; 5,070 women were allocated to equivalent volumes of placebo (normal saline) for loading and maintenance. Main outcomes: The primary outcome was eclampsia. Secondary outcomes included maternal mortality, serious maternal morbidity, and side effects and toxicity from the study drug. For women randomized before delivery, in-hospital death was also a primary outcome and complications of labour and delivery and neonatal morbidity were additional secondary outcomes. Patients and their babies were followed until hospital discharge. Main results: Analysis was intention-to-treat. Clinical characteristics were similar between both groups. Eclampsia occurred less frequently in the magnesium sulfate group (0.8%) than in the placebo group (1.9%). There were no differences in in-hospital baby death; maternal mortality or morbidity; neonatal morbidity; or outcomes related to pregnancy, labour, or delivery except for fewer placental abruptions in the magnesium group (2.0%) than in the placebo group (3.2%; Table). Conclusion: Compared to placebo, magnesium sulfate decreases the risk of eclampsia in women with preeclampsia. Funding: UK Medical Research Council, UK Department for International Development, the UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction. Correspondence: Dr. Lelia Duley, Resource Centre for Randomised Trials, Institute of Health Sciences, Headington, Oxford, OX3 7LF, United Kingdom. Email: [email protected]