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Meta-Analysis
. 2014 Aug 15;2014(8):CD001060.
doi: 10.1002/14651858.CD001060.pub2.

Magnesium sulphate for preventing preterm birth in threatened preterm labour

Caroline A Crowther  1 , Julie Brown, Christopher J D McKinlay, Philippa Middleton
Affiliations
Meta-Analysis

Magnesium sulphate for preventing preterm birth in threatened preterm labour

Caroline A Crowther et al. Cochrane Database Syst Rev. .

Abstract

Background: Magnesium sulphate has been used in some settings as a tocolytic agent to inhibit uterine activity in women in preterm labour with the aim of preventing preterm birth.

Objectives: To assess the effects of magnesium sulphate therapy given to women in threatened preterm labour with the aim of preventing preterm birth and its sequelae.

Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (last searched 31 January 2014).

Selection criteria: Randomised controlled trials of magnesium sulphate as the only tocolytic, administered by any route, compared with either placebo, no treatment or alternative tocolytic therapy (not magnesium sulphate) to women considered to be in preterm labour.

Data collection and analysis: At least two review authors assessed trial eligibility and risk of bias and undertook data extraction independently.

Main results: The 37 included trials (total of 3571 women and over 3600 babies) were generally of moderate to high risk of bias. Antenatal magnesium sulphate was compared with either placebo, no treatment, or a range of alternative tocolytic agents.For the primary outcome of giving birth within 48 hours after trial entry, no significant differences were seen between women who received magnesium sulphate and women who did not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, or human chorionic gonadotropin) (19 trials, 1913 women). Similarly for the primary outcome of serious infant outcome, there were no significant differences between the infants exposed to magnesium sulphate and those not (whether placebo/no alternative tocolytic drug, betamimetics, calcium channel blockers, cox inhibitors, prostaglandin inhibitors, human chorionic gonadotropin or various tocolytic drugs) (18 trials; 2187 babies). No trials reported the outcome of extremely preterm birth. In the seven trials that reported serious maternal outcomes, no events were recorded.In the group treated with magnesium sulphate compared with women receiving antenatal placebo or no alternative tocolytic drug, a borderline increased risk of total death (fetal, neonatal, infant) was seen (risk ratio (RR) 4.56, 95% confidence interval (CI) 1.00 to 20.86; two trials, 257 babies); none of the comparisons between magnesium sulphate and other classes of tocolytic drugs showed differences for this outcome (10 trials, 991 babies). The outcomes of neonatal and/or infant deaths and of fetal deaths did not show differences between magnesium sulphate and no magnesium sulphate, whether compared with placebo/no alternative tocolytic drug, or any specific class of tocolytic drug. For most of the other secondary outcomes, there were no significant differences between magnesium sulphate and the control groups for risk of preterm birth (except for a significantly lower risk with magnesium sulphate when compared with barbiturates in one trial of 65 women), gestational age at birth, interval between trial entry and birth, other neonatal morbidities, or neurodevelopmental outcomes. Duration of neonatal intensive care unit stay was significantly increased in the magnesium sulphate group compared with the calcium channel blocker group, but not when compared with cox inhibitors or prostaglandin inhibitors. No maternal deaths were reported in the four trials reporting this outcome. Significant differences between magnesium sulphate and controls were not seen for maternal adverse events severe enough to stop treatment, except for a significant benefit of magnesium sulphate compared with betamimetics in a single trial.

Authors' conclusions: Magnesium sulphate is ineffective at delaying birth or preventing preterm birth, has no apparent advantages for a range of neonatal and maternal outcomes as a tocolytic agent and its use for this indication may be associated with an increased risk of total fetal, neonatal or infant mortality (in contrast to its use in appropriate groups of women for maternal, fetal, neonatal and infant neuroprotection where beneficial effects have been demonstrated).

PubMed Disclaimer

Conflict of interest statement

Caroline Crowther was the chief investigator for the Australasian multicentred randomised trial of magnesium sulphate given as a cerebroprotective agent to women at risk of very preterm birth (less than 30 weeks' gestation) within 24 hours of expected delivery for the prevention of cerebral palsy and mortality in infants (ACTOMgSO4). CAC and PM are principal investigators on the MAGENTA trial (ACTRN 12611000491965).

Figures

1
1
'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
2
2
'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.
3
3
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.1 Birth < 48 hours after trial entry.
4
4
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.3 Serious infant outcome.
5
5
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.5 Preterm birth (< 37 weeks).
6
6
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.7 Gestational age at birth (weeks).
7
7
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.9 Total deaths (fetal, neonatal and infant).
8
8
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.10 Fetal deaths.
9
9
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.11 Neonatal/infant deaths.
10
10
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.13 Respiratory distress syndrome.
11
11
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.16 IVH (any).
12
12
Funnel plot of comparison: 1 Magnesium sulphate versus comparison group ‐ all included trials, outcome: 1.26 Maternal adverse effects leading to discontinuation of treatment.
1.1
1.1. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 1 Birth < 48 hours after trial entry.
1.2
1.2. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 2 Birth < 24 hours after trial entry.
1.3
1.3. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 3 Serious infant outcome.
1.4
1.4. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 4 Serious maternal outcome.
1.5
1.5. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 5 Preterm birth (< 37 weeks).
1.6
1.6. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 6 Very preterm birth (< 34 weeks).
1.7
1.7. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 7 Gestational age at birth (weeks).
1.8
1.8. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 8 Interval between trial entry and birth (days).
1.9
1.9. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 9 Total deaths (fetal, neonatal and infant).
1.10
1.10. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 10 Fetal deaths.
1.11
1.11. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 11 Neonatal/infant deaths.
1.12
1.12. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 12 Apgar < 7 at 5 minutes.
1.13
1.13. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 13 Respiratory distress syndrome.
1.14
1.14. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 14 Need for assisted ventilation.
1.15
1.15. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 15 Chronic lung disease (oxygen > 28 days of age).
1.16
1.16. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 16 IVH (any).
1.17
1.17. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 17 Severe IVH (Grades 3 or 4)/or PVL.
1.18
1.18. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 18 PVL.
1.19
1.19. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 19 NEC.
1.20
1.20. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 20 Proven neonatal infection (variously defined).
1.21
1.21. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 21 Cerebral palsy.
1.22
1.22. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 22 Maternal death.
1.23
1.23. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 23 Cardiac arrest.
1.24
1.24. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 24 Respiratory arrest.
1.25
1.25. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 25 Admission to intensive care unit.
1.26
1.26. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 26 Maternal adverse effects leading to discontinuation of treatment.
1.27
1.27. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 27 Nausea.
1.28
1.28. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 28 Vomiting.
1.29
1.29. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 29 Nausea and/or vomiting.
1.30
1.30. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 30 Hypotension (variously defined).
1.31
1.31. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 31 Tachycardia (variously defined).
1.32
1.32. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 32 Caesarean.
1.33
1.33. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 33 Admission to neonatal intensive care unit.
1.34
1.34. Analysis
Comparison 1 Magnesium sulphate versus comparison group ‐ all included trials, Outcome 34 Length of stay in neonatal intensive care unit (days).
2.1
2.1. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 1 Birth < 48 hours after trial entry.
2.2
2.2. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 2 Serious infant outcome.
2.3
2.3. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 3 Serious maternal outcome.
2.4
2.4. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 4 Total deaths (fetal, neonatal and infant).
2.5
2.5. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 5 Fetal deaths.
2.6
2.6. Analysis
Comparison 2 Magnesium sulphate for tocolysis (subgrouped by dose), Outcome 6 Neonatal/infant deaths.
See this image and copyright information in PMC

Update of

Comment in

References

References to studies included in this review

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Larmon 1999 {published data only}
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Lorzadeh 2007 {published data only}
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Parsons 1987 {published data only}
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Steer 1977 {published data only}
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Tchilinguirian 1984 {published data only}
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Wilkins 1988 {published data only}
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References to studies excluded from this review

Behrad 2003 {published data only}
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Di Renzo 2005 {published data only}
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Ferguson 1984 {published data only}
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Hatjis 1987 {published data only}
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Herschel 2001 {published data only}
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How 1998 {published data only}
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How 2006 {published data only}
    1. How HY, Zafaranchi L, Stella C, Recht K, Maxwell R, Sibai B, et al. Magnesium sulfate (MGSO4) tocolysis versus no tocolysis in women with preterm labor between 32 0/7 and 34 6/7 weeks of gestation: a randomized controlled trial [abstract]. American Journal of Obstetrics and Gynecology 2005;193(6 Suppl):S6. - PubMed
    1. How HY, Zafaranchi L, Stella CL, Recht K, Maxwell RA, Sibai BM, et al. Tocolysis in women with preterm labor between 32 0/7 and 34 6/7 weeks of gestation: a randomized controlled pilot study. American Journal of Obstetrics and Gynecology 2006;194:976‐81. - PubMed
Ieda 1991 {published data only}
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Kara 2009 {published data only}
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Mittendorf 2000 {published data only}
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Ogburn 1985 {published data only}
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References to studies awaiting assessment

Lotfalizadeh 2010 {published data only}
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References to ongoing studies

Briery 2011 {published data only}
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Sooky 2010 {published data only}
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Additional references

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References to other published versions of this review

Crowther 2002
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Keirse 1995b
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Keirse 1995c
    1. Keirse M. Magnesium sulphate vs betamimetics for tocolysis in preterm labour. [revised 07 April 1994]. In: Enkin MW, Keirse MJNC, Renfrew MJ, Neilson JP, Crowther C (eds.) Pregnancy and Childbirth Module. In: The Cochrane Pregnancy and Childbirth Database [database on disk and CDROM]. The Cochrane Collaboration; Issue 2, Oxford: Update Software; 1995.
Keirse 1995d
    1. Keirse M. Magnesium sulphate vs ethanol for tocolysis in preterm labour. [revised 07 April 1994]. In: Enkin MW, Keirse MJNC, Renfrew MJ, Neilson JP, Crowther C (eds.) Pregnancy and Childbirth Module. In: The Cochrane Pregnancy and Childbirth Database [database on disk and CDROM]. The Cochrane Collaboration; Issue 2, Oxford: Update Software; 1995.

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