Antenatal magnesium sulfate may reduce the excessive rates of cerebral palsy in survivors of very preterm birth. There are five randomized controlled trials of magnesium sulfate therapy given to the mother prior to very preterm birth which have reported neurological outcomes for the child, in four of which the primary aim of the trial was neuroprotection for the fetus. From meta-analysis of these randomized trials, the rate of cerebral palsy was reduced by magnesium sulfate [relative risk (RR) = 0.69; 95% confidence interval (CI) = 0.54-0.87; five trials; 6145 infants). Magnesium sulfate also lowered the rate of substantial motor dysfunction in early childhood (RR = 0.61; 95% CI = 0.44-0.85; four trials; 5980 infants). In addition, where the main aim of the trial was neuroprotection of the fetus, the rates of the combined outcomes of death or cerebral palsy (RR = 0.86; 95% CI = 0.74-0.98; four trials; 4446 infants) and death or substantial motor dysfunction (RR = 0.85; 95% CI = 0.73-0.98; three trials; 4387 infants) were significantly lower with magnesium. On the basis of these findings several countries have now released clinical practice guidelines recommending antenatal magnesium sulfate prior to very preterm birth.