1. ¹Department of Obstetrics and Gynecology, Loyola University Medical Center, Maywood, IL, USA
2. ²Neuroepidemiology Unit, Children's Hospital, Harvard Medical School, Boston, MA, USA
3. ³Perinatal Infectious Disease Epidemiology Unit, Hannover Medical School, Hannover, Germany
4. ⁴Section of Neonatology, Department of Pediatrics, University of Chicago, Chicago, IL, USA

Correspondence: Dr R Mittendorf, Department of Obstetrics and Gynecology, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153, USA. E-mail: rmitten@lumc.edu

Received 23 August 2005; Revised 12 October 2005; Accepted 14 October 2005; Published online 1 December 2005.

Abstract

High-dosage, tocolytic magnesium sulfate (MgSO₄) administered to pregnant women during preterm labor can be toxic, and sometimes lethal, for their newborns (Cochrane Database of Systematic Reviews (relative mortality risk 2.82, 95% confidence interval 1.2–6.6)). Based on the results of the Magnesium and Neurologic Endpoints Trial and the work of many others, a unifying triangular concept is proposed to account for the increased prevalence of brain lesions, with their likely resultant mortality, in neonates and infants exposed to high-dose MgSO₄ in the context of preterm labor. We review the evidence that: (1) elevated circulating levels of serum ionized magnesium occurring in mothers, and therefore in their babies, at the time of delivery are associated with subsequent neonatal intraventricular hemorrhage (IVH); (2) neonatal IVH is strongly associated with lenticulostriate vasculopathy (LSV), an unusual mineralizing lesion involving the thalami and basal ganglia of the neonate; and, (3) exposure to 50 g or more of tocolytic MgSO₄ during preterm labor is associated with the development of LSV.