Does intravenous magnesium sulfate for pregnant individuals at risk of delivery between 30 and 34 weeks’ gestation reduce the risk of death or cerebral palsy in their children?
This randomized clinical trial including 1433 pregnant individuals at risk of preterm delivery and their 1679 infants found no significant difference in death or cerebral palsy at 2 years’ corrected age among children exposed to magnesium sulfate compared with placebo.
Magnesium sulfate prior to preterm birth between 30 and 34 weeks’ gestation did not increase the chance of child survival without cerebral palsy, although this study had limited power to detect an effect.
Intravenous magnesium sulfate administered to pregnant individuals before birth at less than 30 weeks’ gestation reduces the risk of death and cerebral palsy in their children. The effects at later gestational ages are unclear.
To determine whether administration of magnesium sulfate at 30 to 34 weeks’ gestation reduces death or cerebral palsy at 2 years.
Design, Setting, and Participants
This randomized clinical trial enrolled pregnant individuals expected to deliver at 30 to 34 weeks’ gestation and was conducted at 24 Australian and New Zealand hospitals between January 2012 and April 2018.
Intravenous magnesium sulfate (4 g) was compared with placebo.
Main Outcomes and Measures
The primary outcome was death (stillbirth, death of a live-born infant before hospital discharge, or death after hospital discharge before 2 years’ corrected age) or cerebral palsy (loss of motor function and abnormalities of muscle tone and power assessed by a pediatrician) at 2 years’ corrected age. There were 36 secondary outcomes that assessed the health of the pregnant individual, infant, and child.
Of the 1433 pregnant individuals enrolled (mean age, 30.6 [SD, 6.6] years; 46 [3.2%] self-identified as Aboriginal or Torres Strait Islander, 237 [16.5%] as Asian, 82 [5.7%] as Māori, 61 [4.3%] as Pacific, and 966 [67.4%] as White) and their 1679 infants, 1365 (81%) offspring (691 in the magnesium group and 674 in the placebo group) were included in the primary outcome analysis. Death or cerebral palsy at 2 years’ corrected age was not significantly different between the magnesium and placebo groups (3.3% [23 of 691 children] vs 2.7% [18 of 674 children], respectively; risk difference, 0.61% [95% CI, −1.27% to 2.50%]; adjusted relative risk [RR], 1.19 [95% CI, 0.65 to 2.18]). Components of the primary outcome did not differ between groups. Neonates in the magnesium group were less likely to have respiratory distress syndrome vs the placebo group (34% [294 of 858] vs 41% [334 of 821], respectively; adjusted RR, 0.85 [95% CI, 0.76 to 0.95]) and chronic lung disease (5.6% [48 of 858] vs 8.2% [67 of 821]; adjusted RR, 0.69 [95% CI, 0.48 to 0.99]) during the birth hospitalization. No serious adverse events occurred; however, adverse events were more likely in pregnant individuals who received magnesium vs placebo (77% [531 of 690] vs 20% [136 of 667], respectively; adjusted RR, 3.76 [95% CI, 3.22 to 4.39]). Fewer pregnant individuals in the magnesium group had a cesarean delivery vs the placebo group (56% [406 of 729] vs 61% [427 of 704], respectively; adjusted RR, 0.91 [95% CI, 0.84 to 0.99]), although more in the magnesium group had a major postpartum hemorrhage (3.4% [25 of 729] vs 1.7% [12 of 704] in the placebo group; adjusted RR, 1.98 [95% CI, 1.01 to 3.91]).
Conclusions and Relevance
Administration of intravenous magnesium sulfate prior to preterm birth at 30 to 34 weeks’ gestation did not improve child survival free of cerebral palsy at 2 years, although the study had limited power to detect small between-group differences.
anzctr.org.au Identifier: ACTRN12611000491965
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Accepted for Publication: June 16, 2023.
Corresponding Author: Caroline A. Crowther, MD, Liggins Institute, University of Auckland, Private Bag 92019, Victoria St W, Auckland 1142, New Zealand (firstname.lastname@example.org).
Author Contributions: Drs Crowther and Tran had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Crowther, Middleton, Harding.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Crowther, Middleton, Tran, Harding.
Statistical analysis: Tran.
Obtained funding: Crowther, Ashwood, Middleton, McPhee, Harding.
Administrative, technical, or material support: Crowther, Ashwood, Middleton, McPhee, Harding.
Supervision: Crowther, Ashwood, Middleton, McPhee, Harding.
Conflict of Interest Disclosures: None reported.
Funding/Support: This trial was funded by grant 1022968 from the National Health and Medical Research Council in Australia and grants PG5716 and PG01817 from the Cerebral Palsy Alliance Research Foundation Australia.
Role of the Funder/Sponsor: The funders/sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Group Information: A complete list of the members of the MAGENTA Study Group appears in Supplement 4.
Data Sharing Statement: See Supplement 5.
Additional Contributions: We thank the 1433 pregnant individuals and their children who participated in this trial.
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