Objective: To evaluate the association of duration of magnesium sulfate infusion with stillbirth or death, cerebral palsy, and select adverse maternal and neonatal outcomes.
Methods: This is a secondary cohort analysis of women randomized to receive magnesium sulfate within a previously reported Maternal-Fetal Medicine Units Network prospective clinical trial. The association of antenatal infusion of magnesium sulfate for less than 12 hours, 12-18 hours, and greater than 18 hours on maternal and perinatal outcomes was compared. The primary outcome was cerebral palsy of any severity or death. Secondary outcomes included cerebral palsy, death, and select maternal and neonatal outcomes. Stratified and logistic regression analyses were used. The models were adjusted for race, gestational age at birth, time since last magnesium sulfate, any magnesium sulfate at delivery, and eligibility criteria as appropriate.
Results: Of 933 women available for analysis, 356, 341, and 236 received antenatal magnesium sulfate infusion for a total of less than 12 hours, 12-18 hours, or greater than 18 hours, respectively. Any cerebral palsy or death occurred in 39 women (11.7%) who received magnesium sulfate less than 12 hours, 34 women (10.3%) who received 12-18 hours of magnesium sulfate, and 20 women (8.8%) who received greater than 18 hours of magnesium sulfate. There was no difference in death or cerebral palsy among groups (less than 12 hours as reference; adjusted odds ratio [OR] 1.03, 95% confidence interval [CI] 0.60-1.77 for 12-18 hours; adjusted OR 1.08, 95% CI 0.57-2.03 for greater than 18 hours). Select maternal adverse drug affects and neonatal morbidities were also similar across groups.
Conclusion: The duration of antenatal magnesium sulfate infusion is not associated with risk of death or cerebral palsy. The optimal treatment duration needed for maximal neuroprotection remains unknown.
Level of evidence: : II.