Can Magnesium Sulfate Reduce the Risk of Cerebral Palsy in Very Low Birthweight Infants?

OBJECTIVES: To investigate whether in utero exposure to magnesium sulfate (MgSO4) was associated with a lower prevalence of cerebral palsy (CP) in infants born weighing < 1500 g. DESIGN: Singleton infants weighing < 1500 g at birth (very low birthweight, VLBW) and surviving to 3 years with moderate or severe congenital CP were identified among 155,636 children born 1983 through 1985 in four California counties. VLBW children with CP were compared with randomly selected VLBW control survivors with respect to whether their mothers received MgSO4 to prevent convulsions in preeclampsia or as a tocolytic agent, and other information abstracted from labor and delivery records. RESULTS: During the admission for delivery, 7.1% of the 42 VLBW infants with later CP and 36% of the 75 VLBW controls were exposed to MgSO4 (odds ratio (OR) .14, 95% confidence interval (CI) .05, .51). The overall association of MgSO4 with reduced risk of CP was also observed in the subgroup of infants born to women who were not preeclamptic (OR .25, CI .08, .97). Infants with CP were less often exposed antenatally to MgSO4 whether or not there was cotreatment with non-MgSO4 tocolytics (other tocolytics administered, OR for MgSO4 exposure .23, CI .06, 1.2; other tocolytics not administered, OR for MgSO4 .08, CI .02, .68), or antenatal corticosteroids (steroids given, OR for MgSO4 exposure .24, CI .06, 1.3; steroids not given, OR for MgSO4, .08, CI .02, .72). Apparent benefit of magnesium was observed in the presence or absence of a variety of characteristics of pregnancies, births, and infants. CONCLUSION: In this observational study, in utero exposure to MgSO4 was more frequent in controls than in children with CP, suggesting a protective effect of MgSO4 against CP in these VLBW infants.