Maternal & Newborn Atlas
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Magnesium sulfate to prevent and treat eclampsia

Magnesium sulfate is a medicine given by injection or drip to women with pre-eclampsia to lower the chance of a seizure, and to women who have had a seizure to stop more. In the Magpie trial it cut seizures in women with pre-eclampsia by more than half. In the Collaborative Eclampsia Trial it worked better than diazepam or phenytoin at stopping repeat seizures. It also caused side-effects, and it did not clearly change the risk of the baby dying.

  • Intervention
  • In this atlas

Overview

Technical summary

Medicine strategy for eclampsia and pre-eclampsia, kept apart from magnesium sulfate for the baby's brain protection before early preterm birth, which is a different use recorded elsewhere in this atlas; evidence for one use does not apply to the other. Two claims sit here: the Collaborative Eclampsia Trial (treatment of eclampsia against diazepam and phenytoin) and the Magpie trial (prevention of eclampsia against placebo, with a separate claim on death of the baby). Dose and route are not given in the abstracts and are not recorded. Sources are PubMed abstracts only.

About this intervention

Type
Medicine
Mechanism
Not reported

Claims and evidence

Context Babies of women with pre-eclampsia randomised before delivery (Magpie)

Recipient
Mixed recipients
Population
The babies of women who were randomised before delivery, counted from the time of randomisation, so fetal and newborn deaths are counted together as death of the baby. Use this context only for that outcome.
Care setting
Not stated in the source
Geography
33 countries; the abstract does not name them
Life stage
Pregnancy, until birth, and the newborn period
Gestational age
Not reported
Postnatal age
Not reported
Follow-up
Follow-up was until discharge from hospital after delivery.
Eligibility: 1 inclusion criterion; exclusion criteria not stated
Included
  • Babies of women with pre-eclampsia randomised before delivery
Excluded
None stated

  • Effect Interventional Certainty not assessed

    For women randomised before delivery in the Magpie trial, there was no clear difference in the risk of the baby dying: 576 babies (12.7%) in the magnesium sulphate group against 558 (12.4%) in the placebo group (relative risk 1.02, 99% CI 0.92 to 1.14). Death of the baby was a primary outcome of the trial, alongside eclampsia.

    Applies to Mixed recipients
    • The babies of women who were randomised before delivery, counted from the time of randomisation, so fetal and newborn deaths are counted together as death of the baby. Use this context only for that outcome.
    • Not stated in the source
    • 33 countries; the abstract does not name them
    • Pregnancy, until birth, and the newborn period
    • Gestational age Not reported
    • Postnatal age Not reported
    Follow-up Follow-up was until discharge from hospital after delivery.
    Certainty method
    Not assessed
    Limitations
    This is a null result as reported, for the babies of women randomised before delivery. The abstract gives the number of deaths and percentages but no denominators, so none are computed. The result says nothing about magnesium sulfate given to women for fetal protection before early preterm birth, which is a separate use with its own trial evidence in another record. Only the PubMed abstract was read.
    Last checked
    2026-10-14
    Next evidence check due
    Not scheduled
    Sources and citations (2)

    1. Supports Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. · Published 2002-06-01 · DOI: 10.1016/s0140-6736(02)08778-0 · PMID: 12057549

      Locator
      Abstract, METHODS, sentences 2 and 3: groups and primary outcomes
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      89dad4b9c1c1e96396fa90fbd58c8272b6eb3891a7f0b73066a9a511183cf19d
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    2. Supports Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. · Published 2002-06-01 · DOI: 10.1016/s0140-6736(02)08778-0 · PMID: 12057549

      Locator
      Abstract, FINDINGS, sentence 5: death of the baby
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      89dad4b9c1c1e96396fa90fbd58c8272b6eb3891a7f0b73066a9a511183cf19d
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

Context Women with eclampsia in the Collaborative Eclampsia Trial (1995)

Recipient
Maternal
Population
Women with eclampsia, a seizure in association with pre-eclampsia, recruited into an international multicentre randomised trial that compared standard anticonvulsant regimens. 1687 women were recruited; data are available for 1680 (453 allocated magnesium sulphate against 452 allocated diazepam, and 388 allocated magnesium sulphate against 387 allocated phenytoin). Use this context only for the maternal outcomes of these comparisons.
Care setting
Not stated in the source
Geography
International; the abstract does not name the countries
Life stage
Pregnancy, labour or after birth; the abstract does not say when the seizure occurred
Gestational age
Not reported
Postnatal age
Not reported
Follow-up
Follow-up is not given in the abstract.
Eligibility: 1 inclusion criterion; exclusion criteria not stated
Included
  • Women with eclampsia
Excluded
None stated

  • Effect Interventional Certainty not assessed

    The Collaborative Eclampsia Trial randomly compared anticonvulsants in 1687 women with eclampsia. Women allocated magnesium sulphate had a 52% lower risk of recurrent convulsions than those allocated diazepam (60 of 453 women, 13.2%, against 126 of 452, 27.9%; 95% CI 64% to 37% reduction), and a 67% lower risk than those allocated phenytoin (22 of 388, 5.7%, against 66 of 387, 17.1%; 95% CI 79% to 47% reduction). Maternal mortality was non-significantly lower with magnesium sulphate in both comparisons. The authors conclude there is compelling evidence in favour of magnesium sulphate, rather than diazepam or phenytoin, for the treatment of eclampsia.

    Source problem. A cited source is corrected. Check the sources before relying on this claim.

    Applies to Maternal
    • Women with eclampsia, a seizure in association with pre-eclampsia, recruited into an international multicentre randomised trial that compared standard anticonvulsant regimens. 1687 women were recruited; data are available for 1680 (453 allocated magnesium sulphate against 452 allocated diazepam, and 388 allocated magnesium sulphate against 387 allocated phenytoin). Use this context only for the maternal outcomes of these comparisons.
    • Not stated in the source
    • International; the abstract does not name the countries
    • Pregnancy, labour or after birth; the abstract does not say when the seizure occurred
    • Gestational age Not reported
    • Postnatal age Not reported
    Follow-up Follow-up is not given in the abstract.
    Certainty method
    Not assessed
    Limitations
    The comparison is magnesium sulphate against diazepam and against phenytoin in women who already had eclampsia; there was no placebo group, and the result is about treating seizures, not preventing them (the Magpie claim is about prevention in pre-eclampsia). The trial dates from 1995. PubMed lists a published erratum (Lancet 1995;346:258) that has no PubMed record and was not read. The abstract also reports outcomes for the babies of the women allocated magnesium sulphate before delivery, which belong to a newborn context and are not summarised here. Only the abstract was read.
    Last checked
    2026-10-14
    Next evidence check due
    Not scheduled
    Sources and citations (4)

    1. Supports Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. PubMed lists a published erratum (Lancet 1995;346:258) that has no PubMed record and was not read; the snapshot is marked corrected because of that erratum, whose content is not known. · Published 1995-06-10 · PMID: 7769899

      Locator
      Abstract, sentences 3 to 5: design and numbers analysed
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Corrected
      Snapshot hash
      d51443591607df5b330709effbd6b72aa681fd190e5e8e62ce475473e8dc6e14
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    2. Supports Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. PubMed lists a published erratum (Lancet 1995;346:258) that has no PubMed record and was not read; the snapshot is marked corrected because of that erratum, whose content is not known. · Published 1995-06-10 · PMID: 7769899

      Locator
      Abstract, sentences 7 to 11: recurrent convulsions and maternal mortality
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Corrected
      Snapshot hash
      d51443591607df5b330709effbd6b72aa681fd190e5e8e62ce475473e8dc6e14
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    3. Supports Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. PubMed lists a published erratum (Lancet 1995;346:258) that has no PubMed record and was not read; the snapshot is marked corrected because of that erratum, whose content is not known. · Published 1995-06-10 · PMID: 7769899

      Locator
      Abstract, sentence 14: authors' conclusion
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Corrected
      Snapshot hash
      d51443591607df5b330709effbd6b72aa681fd190e5e8e62ce475473e8dc6e14
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    4. Background Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. PubMed lists a published erratum (Lancet 1995;346:258) that has no PubMed record and was not read; the snapshot is marked corrected because of that erratum, whose content is not known. · Published 1995-06-10 · PMID: 7769899

      Locator
      Abstract, sentence 13: babies' outcomes (not summarised)
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Corrected
      Snapshot hash
      d51443591607df5b330709effbd6b72aa681fd190e5e8e62ce475473e8dc6e14
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

Context Women with pre-eclampsia who had not given birth or were within 24 hours after birth (Magpie)

Recipient
Maternal
Population
Women with pre-eclampsia, defined by blood pressure of 140/90 mm Hg or more and proteinuria of 1+ (30 mg/dL) or more, who had not given birth or were 24 hours or less postpartum, and for whom there was clinical uncertainty about magnesium sulphate. Randomised in 33 countries. Use this context for the maternal outcomes eclampsia and maternal death.
Care setting
Not stated in the source
Geography
33 countries; the abstract does not name them
Life stage
Pregnancy or up to 24 hours after birth
Gestational age
Not reported
Postnatal age
Not reported
Follow-up
Follow-up was until discharge from hospital after delivery.
Eligibility: 3 inclusion criteria; exclusion criteria not stated
Included
  • Pre-eclampsia (blood pressure 140/90 mm Hg or more and proteinuria 1+ or more)
  • Not yet given birth, or 24 hours or less postpartum
  • Clinical uncertainty about magnesium sulphate
Excluded
None stated

  • Effect Interventional Certainty not assessed

    In the Magpie trial, 10,141 women with pre-eclampsia who had not given birth or were within 24 hours after birth were randomised in 33 countries to magnesium sulphate (5071 women) or placebo (5070 women). Women allocated magnesium sulphate had a 58% lower risk of eclampsia (95% CI 40 to 71) than those allocated placebo (40 women, 0.8%, against 96, 1.9%; 11 fewer women with eclampsia per 1000 women). Maternal mortality was also lower with magnesium sulphate, with a wide interval that includes no effect (relative risk 0.55, 0.26 to 1.14). Side-effects were reported by 1201 of 4999 women (24%) given magnesium sulphate against 228 of 4993 (5%) given placebo. The authors conclude there do not appear to be substantive harmful effects to mother or baby in the short term.

    Applies to Maternal
    • Women with pre-eclampsia, defined by blood pressure of 140/90 mm Hg or more and proteinuria of 1+ (30 mg/dL) or more, who had not given birth or were 24 hours or less postpartum, and for whom there was clinical uncertainty about magnesium sulphate. Randomised in 33 countries. Use this context for the maternal outcomes eclampsia and maternal death.
    • Not stated in the source
    • 33 countries; the abstract does not name them
    • Pregnancy or up to 24 hours after birth
    • Gestational age Not reported
    • Postnatal age Not reported
    Follow-up Follow-up was until discharge from hospital after delivery.
    Certainty method
    Not assessed
    Limitations
    The authors' summary that magnesium sulphate probably reduces the risk of maternal death rests on a relative risk whose interval includes no effect. The only notable difference in maternal or neonatal morbidity was for placental abruption (relative risk 0.67, 99% CI 0.45 to 0.89); other morbidity was not summarised. This claim is about the women. Death of the baby is a separate claim and a separate context. Only the PubMed abstract was read; the full text and the registry record were not. The ISRCTN number is not used because the PubMed record does not print it.
    Last checked
    2026-10-14
    Next evidence check due
    Not scheduled
    Sources and citations (3)

    1. Supports Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. · Published 2002-06-01 · DOI: 10.1016/s0140-6736(02)08778-0 · PMID: 12057549

      Locator
      Abstract, METHODS: population, groups and primary outcomes
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      89dad4b9c1c1e96396fa90fbd58c8272b6eb3891a7f0b73066a9a511183cf19d
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    2. Supports Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. · Published 2002-06-01 · DOI: 10.1016/s0140-6736(02)08778-0 · PMID: 12057549

      Locator
      Abstract, FINDINGS, sentences 2 to 4 and 6: side-effects, eclampsia, maternal mortality, other morbidity
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      89dad4b9c1c1e96396fa90fbd58c8272b6eb3891a7f0b73066a9a511183cf19d
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

    3. Supports Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? The Magpie Trial: a randomised placebo-controlled trial

      Publication · Lancet (London, England) · Edition PubMed record (abstract and bibliographic data) from NCBI E-utilities. The full text and the version of record were not fetched. · Published 2002-06-01 · DOI: 10.1016/s0140-6736(02)08778-0 · PMID: 12057549

      Locator
      Abstract, INTERPRETATION, sentence 2
      How it applies
      PubMed abstract.
      Retrieved
      Source effective date
      Not reported
      Source state
      Current
      Snapshot hash
      89dad4b9c1c1e96396fa90fbd58c8272b6eb3891a7f0b73066a9a511183cf19d
      Reuse basis
      PubMed record fetched through NCBI E-utilities. Only the hash of the bytes is kept, because publisher copyright may apply to the abstract (https://pubmed.ncbi.nlm.nih.gov/disclaimer/). Short factual quotations under 25 words, with the citation.

Clinical links

Each link reports what one cited claim says about one population. "Evaluated for" means studied, not shown to work. These links do not show that anything is effective or right for you.

Record details

Record id
maternal:magnesium-sulfate-eclampsia
Content hash
f001231f39265f008aa2d5571473eafe5c8f9379cc94c85b56c3bfbcf89ffc7d