Neonatal Hypermagnesemia After in Utero Exposure to Magnesium Sulfate: Case Report

Abstract

Magnesium sulfate (MgSO4) is currently the treatment of choice for severe preeclampsia and eclampsia. However, the risk and potential effects of neonatal hypermagnesemia are not well- recognized. The authors report the case of a late preterm male neonate whose mother was treated with MgSO4 for severe preeclampsia. Maternal hypermagnesemia, hypertension, and neurological worsening motivated emergency cesarean section. At his first minute of life, the newborn was bradycardic, cyanotic, hypotonic, and did not start to breathe spontaneously. Neonatal resuscitation was performed, requiring endotracheal intubation and immediate admission to the Neonatal Unit for mechanical ventilation and continuous cardiorespiratory monitoring. The immeasurable plasmatic magnesium level was compatible with the diagnosis of hypermagnesemia. Symptoms and signs slowly disappeared as magnesium values normalized and respiratory function was fully recovered hours later. This case shows a rare but reversible cause of neonatal respiratory depression and hypotonia in the context of maternal MgSO4 infusion.