To study the relationship between antenatal maternal magnesium dosing and neonatal serum magnesium levels.METHODS:
A retrospective study was conducted on mothers who delivered at less than 34 weeks gestation after receiving antenatal magnesium. The dose of magnesium infused to the mother within seven days of delivery was correlated with neonatal serum magnesium concentrations in the first 24 hours of life using Spearman correlation. We calculated the maternal magnesium dose as “continuous dose” and “cumulative dose.” Continuous dose only took into account the magnesium received by the mother as a continuous infusion before delivery; interruption for more than 4 hours (half-life of magnesium) was considered as not “continuous.” Cumulative dose included all magnesium received by the mother regardless of interruptions.RESULTS:
Of the 237 mothers/baby dyads delivering during the study period, 202 neonates had serum magnesium concentration checked within 24 hours of birth. Neonatal magnesium concentration correlated more strongly with continuous dose (r=0.652, P<.0001) than with cumulative dose (r=0.548, P<.0001). The correlation of neonatal magnesium concentration with cumulative dose for the three days before delivery (r=0.657, P<.0001) was similar to its correlation with continuous dose; for cumulative doses from 4, 5, 6 or 7 days before delivery, the correlations though statistically significant at P<.0001, became gradually weaker (r=0.611; r=0.583; r=0.558; and r=0.548, respectively).CONCLUSION:
Neonatal magnesium concentrations correlates better with continuous magnesium dose, suggesting that interruption in magnesium infusion for 4 or more hours may be associated with lower neonatal magnesium levels, which might be associated with a decrease in neonatal morbidity and mortality.