Despite known racial disparities in obstetrics, as well as differences in magnesium pharmacodynamics according to race, the effect of race/ethnicity in magnesium sulfate (MgSO4) use during pregnancy has not been studied. Whether some mothers are at increased risk of side effects, or infants at decreased neuroprotective effects is unknown. We analyze the effect of race/ethnicity in maternal/infant outcomes after MgSO4 neuroprotection.