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Antenatal magnesium sulphate is neuroprotective for infants born preterm
Clinical Question
Does magnesium sulphate provide neuroprotective benefits for infants when administered to their mothers prior to preterm birth?
Bottom line
Magnesium sulphate administered to mothers prior to preterm birth reduces the risk of cerebral palsy (CP) in their offspring (number needed to treat [NNT] = 48). The most common regimen was 4 g intravenously with or without a maintenance infusion of 1 g per hour. There were no serious adverse events for mothers, although an adverse maternal event leading to stopping treatment was seen more often among the women given magnesium (number needed to treat to harm [NNTH] = 40). This meta-analysis demonstrates sufficient strength of evidence to prompt widespread implementation. 1a
Reference
Study design: Meta-analysis (randomized controlled trials)
Funding: Government
Setting: Various (meta-analysis)
Synopsis
This was a carefully designed and executed meta-analysis including 5 randomized controlled trials (N = 5493 women and 6131 infants) to assess the neuroprotective effect of antenatal administration of magnesium sulphate prior to preterm birth. Individual patient data were obtained from the authors of each trial for the analysis. Studies were included if data to assess the neurological outcomes of the infants were available, whether or not the use of magnesium sulphate was intended for neuroprotection. The included studies were assessed for risk of bias, which was generally low or unclear. The first primary outcome was a composite of fetal/infant death or CP as defined by the trialists and categorized as mild, moderate, or severe. This was found to favor the treatment, with borderline statistical significance (15.1% vs 17.4%; relative risk [RR] 0.86; 95% CI 0.75 - 0.99). Of the 2 components, the number of deaths was not significantly different (RR 1.03; 0.91 - 1.17). However, CP was reduced in the treated groups (4.7% vs 6.7%; RR 0.68; 0.54 - 0.87; NNT = 48; 29 - 133). The second primary outcome was any severe maternal outcome related to treatment; there were none. Maternal adverse events leading to stoppage of treatment were more frequent in the magnesium sulphate groups (5.0% vs 2.5%; RR 1.95; 1.44 - 2.65; NNTH = 40; 28 - 71). Multiple subgroup analyses were conducted suggesting that benefit was seen regardless of preterm gestational age range or specific treatment regimen. The most common regimens were a 4 g IV bolus with or without maintenance infusion of 1 g per hour.
Reviewer
Linda Speer, MD
Professor and Chair, Department of Family Medicine
University of Toledo
Toledo, OH
Comments
The clear importance of the use of mag sulphate in the prevention of cerebral palsy has been known for many years now and it is surprising that this is still the subject of a review rather than being promoted more actively as set guidelines.
is this recommended for all pregnancies, or for those with PIH?
I'm not clear if the improved outcome was for severe PIH, or for normal pregnancies. If for all pregnancies it means an IV for all, implications for home deliveries and those desiring a natural birth as possible.
Good poem