Association of hypermagnesemia at birth and admission hypothermia in pre-term infants: A secondary analysis of a prospective cohort study.

Abstract

BACKGROUND Hypothermia on admission is associated with increased mortality in preterm infants. Drugs administered to pregnant women is implicated in its occurrence. Since magnesium sulfate has a myorelaxant effect, we aimed evaluating the association of hypermagnesemia at birth and admission hypothermia (axillary temperature <36.5°C) in preterm infants. METHODS We performed a secondary analysis of a prospective cohort study database including inborn infants <34 weeks, without congenital malformations. Hypermagnesemia was considered if the umbilical magnesium level >  2.5 mEq/L. Maternal and neonatal variables were used to adjust the model, submitted to the multivariate hierarchical modelling process. RESULTS We evaluated 249 newborns with median birth weight and gestational age of 1375 (IQR 1020-1375) g and 31 (IQR 28-32) weeks, respectively. Hypermagnesemia occurred in 28.5% and admission hypothermia occurred in 28.9% . In the univariate analysis, the following variables were identified as being associated with admission hypothermia: hypermagnesemia (OR 3.71; CI 2.06-6.68), resuscitation (OR 2.39; CI 1.37-4.19), small to gestational age (OR 1.91; CI1.03-3.53), general anesthesia (OR 3.34; CI 1.37-8.13), birth weight (OR 0.998; CI 0.998-0.999) and gestational age (OR 0.806; CI 0.725-0.895). In the hierarchical regression model, hypermagnesemia remained independent associated with admission hypothermia (OR 3.20; CI 1.66-6.15), as well as birth weight (OR 0.999; CI 0.998-0.999) and tracheal intubation (3.83; CI 1.88-7.80). CONCLUSION Hypermagnesemia was associated with an increased risk of admission hypothermia, as did tracheal intubation and lower birth weight.