Does Magnesium Help Prevent Cerebral Palsy?

Lex W Doyle MD BS MSc FRACP Professor of Neonatal Paediatrics Department of Obstetrics and Gynaecology The Royal Women’s Hospital Parkville, Victoria, Interview with:
Professor of Neonatal Paediatrics
Department of Obstetrics and Gynaecology
The Royal Women’s Hospital
Parkville, Victoria, Australia

Medical Research: What are the main findings of the study?

Dr. Doyle: From collectively pooling data from five large trials carried out around the world over the past 20 years, we know that magnesium sulfate given under strict medical protocols in hospital to women threatening to deliver preterm reduces the risk of cerebral  palsy in their children in early childhood.  Following  from this knowledge, magnesium sulfate is now given routinely to women, under strict medical conditions, who are threatening to deliver very early in Australia, and in other parts of the world, to try to prevent cerebral palsy in their child.  What we do not know is if magnesium sulfate used this way has any longer-term effects on the brain or on other important outcomes.

One of the initial studies that contributed to the overall evidence about cerebral palsy was carried out in Australia and New Zealand and completed more than 10 years ago.  Over 1000 women and their babies were enrolled in that study and although the rate of cerebral palsy was not substantially reduced by magnesium sulfate in our study, we showed that there were fewer children at 2 years of age who were not walking in the group whose mothers were given magnesium compared with those whose mothers were given placebo.  With this knowledge, and given the unknown longer-term benefits or risks, we re-evaluated the children from our study at school-age, between 6-11 years of age.  We thoroughly evaluated their brain function, including movement and co-ordination, thinking ability, behaviour, and school progress, as well as general health and well-being.  The basic message from our longer-term study is that magnesium sulfate, as used in our trial, does not have any substantial benefits or harms on brain or cognitive function, or any other outcome at school age.

Medical Research: Were any of the findings unexpected?

Dr. Doyle: Given that walking was improved at 2 years, we hoped that magnesium sulfate might improve motor function or co-ordination at school-age, but it did not do so.

Medical Research: What should clinicians and patients take away from your report?

Dr. Doyle: What this means for those who are currently using magnesium sulfate to prevent cerebral palsy in very preterm infants is that there is no evidence for longer-term harm to the children from this practice, so they should continue.  On the other hand, for those who are yet to decide to use magnesium sulfate to prevent cerebral palsy, the longer-term data does not help to convince them otherwise.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Doyle: What is required now is for all of the original trials to try to re-evaluate the children enrolled in their studies at school-age.  Then the total amount of data can be combined, as we did when the outcomes in early childhood were available, to try to establish any longer-term outcomes that may be important for the children and their families.


Doyle LW, Anderson PJ, Haslam R, Lee KJ, Crowther C, for the Australasian Collaborative Trial of Magnesium Sulphate (ACTOMgSO4) Study Group. School-age Outcomes of Very Preterm Infants After Antenatal Treatment With Magnesium Sulfate vs Placebo. JAMA. 2014;312(11):1105-1113. doi:10.1001/jama.2014.11189.