Antenatal magnesium sulphate for the prevention of cerebral palsy in infants born preterm: a double-blind, randomised, placebo-controlled, multi-centre trial

Objective To study the effect of antenatal magnesium sulphate (MgSO4) on cerebral palsy (CP) in a manner that also provides adequate power for a linked trial sequential analysis. Design Double-blind, randomised, placebo-controlled, multi-centre trial. Setting Fourteen Danish obstetric departments. Population In total, 560 pregnant women at risk for preterm delivery before 32 weeks of gestation were randomised from December 2011 to January 2018. Those women gave birth to 680 children. Methods Women were randomised to receive either a loading dose of 5 g MgSO4 followed by 1 g/hour or a placebo in identical volumes. The children were followed up at a corrected age of 18 months or older with a review of their medical charts and with the Ages and Stages Questionnaire. Main outcome measure The primary outcome measure was moderate to severe CP. Secondary outcomes included mortality, neonatal morbidity, blindness and mild CP. Results The crude rates of moderate to severe CP in the MgSO4 group and the placebo group were 2.0% and 3.3%, respectively. The adjusted odds of moderate to severe CP were lower in the MgSO4 group than in the placebo group (odds ratio 0.61; 95% CI 0.23-1.65). Conclusions Antenatal MgSO4 before 32 weeks of gestation decreases the likelihood of moderate to severe CP; these results are entirely consistent with other randomised evidence summarised in the linked trial sequential analysis. Tweetable abstract Antenatal magnesium sulphate may decrease the risk of moderate to severe cerebral palsy in children born before 32 weeks of gestation.