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evident
Original paper
2002LancetOB/GYN

MAGPIE

Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial

RCTPreeclampsia

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Overview

Magnesium sulfate roughly halved eclampsia risk in women with preeclampsia.

Clinical takeaway

MAGPIE established magnesium sulfate as the standard seizure-prevention therapy for preeclampsia, especially severe disease.

Key result

Eclampsia was reduced by about 58% with magnesium sulfate.

Practice impact

Magnesium sulfate became routine prophylaxis for severe preeclampsia and treatment/prevention around eclampsia.

Evidence

Study design

Large randomized, placebo-controlled trial.

Enrollment

10,141

Follow-up

Until hospital discharge for main maternal outcomes.

Geography

Multinational

Clinical question

Does magnesium sulfate prevent eclampsia and improve outcomes in women with preeclampsia?

Population

  • Pregnant or recently delivered women with preeclampsia for whom there was clinical uncertainty about magnesium sulfate.

Intervention

Magnesium sulfate regimen.

Comparator

Placebo.

Primary outcome

Eclampsia and, for women randomized before delivery, death of the baby.

Magnesium sulfate substantially reduced the risk of eclampsia among women with preeclampsia.

Relative risk / 0.42 / 95% CI 0.29-0.60

Key results

  • Eclampsia: 0.8% (40 women) with magnesium sulfate vs 1.9% (96) with placebo; 58% lower risk (95% CI 40-71), or 11 fewer women with eclampsia per 1000.
  • Maternal mortality was lower with magnesium sulfate but not significantly (RR 0.55; 95% CI 0.26-1.14).
  • For women randomized before delivery, death of the baby did not clearly differ (12.7% vs 12.4%; RR 1.02; 99% CI 0.92-1.14).
  • Side effects were reported by 24% with magnesium sulfate vs 5% with placebo, but serious toxicity was uncommon with monitoring.

Harms

  • Flushing and other minor side effects were common.
  • Respiratory depression and loss of reflexes are toxicity concerns requiring monitoring.

Clinical Use

Practice impact

  • Made magnesium sulfate standard for seizure prophylaxis in severe preeclampsia and treatment of eclampsia.

Applicability

  • Women with preeclampsia, especially severe features or high seizure risk.

Limitations

  • Absolute benefit varies by baseline eclampsia risk.
  • Requires clinical monitoring, reflex checks, respiratory assessment, and renal-dose awareness.

Common misinterpretations

  • Magnesium prevents seizures; it is not an antihypertensive treatment for severe-range blood pressure.

Related evidence

CHAP - Same DiseaseASPRE - Context

Citation

Altman D, Carroli G, Duley L, et al. Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial. Lancet. 2002;359(9321):1877-1890. doi:10.1016/s0140-6736(02)08778-0

Magnesium sulphate halves the risk of eclampsia, and probably reduces the risk of maternal death.