Hypermagnesemia in preterm neonates exposed to antenatal magnesium sulfate.

BACKGROUND: One of the possible adverse outcomes of magnesium sulfate (MgSO4) administration for preterm fetal neuroprotection is hypermagnesemia in the newborn. The objectives of this study were to evaluate the association between antenatal MgSO4 administration for neuroprotection and neonatal serum magnesium levels in the first days of life.

METHODS: A single-center retrospective case-control study was conducted on preterm neonates born in our institution between January 2017 and December 2019. Prenatal, perinatal, and postnatal parameters were recorded, and demographic information was collected. Comparative analysis between the group of neonates exposed to antenatal MgSO4 and the control group was performed.

RESULTS: A total of 98 patients were enrolled in the study, 49 of them were exposed to antenatal MgSO4 for neuroprotection. The serum magnesium levels in the 5 first days of life were higher in the case group, and higher than the normal range of serum magnesium levels (>2.4 mg/dL), with a statistical significance. The number of days needed to normalize serum magnesium levels was higher in the case group compared to the control group (median of 7 days [1-8] versus 2 days [1-5]).

CONCLUSIONS: Our findings show that antenatal administration of MgSO4 is associated with high serum magnesium levels in neonates. This group of patients needs close electrolyte monitoring during the first days of life. Parenteral nutrition supplemented with magnesium should only be considered after evaluation of serum magnesium levels.