Objective: To evaluate the association of cord blood magnesium concentrations at the time of birth with cerebral palsy (CP) and neonatal death. Study Design: A secondary analysis of a randomized controlled trial that randomized women at imminent risk of delivery between 24 and 31 weeks of gestation to receive magnesium sulfate or placebo. This ‘study’s primary outcome was a composite of either moderate to severe CP or death. Secondary outcomes included CP, moderate to severe CP, neonatal death, and neonatal head ultrasound findings. We used a logistic regression model to evaluate the relationship between the concentration of magnesium in cord blood and study outcomes. Results: A total of 668 women were included in this analysis and were randomized to magnesium sulfate at 28 ± 2.5 ‘weeks’ gestation. Cord blood magnesium concentrations were not associated with the primary outcome of infant death by 1 year of age or moderate or severe cerebral palsy, as assessed at or beyond 2 years of age (aOR 0.95 (0.67, 1.36), p = 0.79). Cord blood magnesium concentrations were not associated with any of the secondary outcome measurements. Conclusion: Cord blood magnesium concentrations were not associated with moderate to severe cerebral palsy or death, or other neurodevelopmental or sonographic outcomes