CORRELATION BETWEEN MATERNAL CUMULATIVE DOSE OF INTRAPARTUM MAGNESIUM SULFATE AND CORD BLOOD MAGNESIUM LEVEL

Magnesium sulfate (MgSO4) is given for several obstetric indications, even though its adverse effect on newly born infants is of major concern. The aim of this study was to investigate the relationship between maternal cumulative dose of magnesium sulfate (M-Mg) and cord blood magnesium (C-Mg) concentration. Sixty-three infants from 57 mothers who received intrapartum MgSO4 were enrolled. The median gestational age was 37 weeks and the median 1- and 5-minute Apgar scores were both greater than 7. Median [interquartile range] M-Mg level and median duration of MgSO4 infusion was 18.4 [9.9, 40.9] grams and 6.7 [2.9, 14.4] hours, respectively. The mean +/- standard deviation C-Mg was 4.5 +/- 1.3 mg/dl. The relationship between M-Mg and C-Mg was non-linear, with a correlation coefficient (r) of 0.55. Eight infants (12.7%) developed apneic episodes. There were no significant differences in mean C-Mg and mean M-Mg levels between infants with and without apnea [5.2 +/- 1.9 vs 4.4 +/- 1.2 mg/dl; p=0.32; and, 17.8 +/- 22.6 vs 58.3 +/- 69.6 mg/dl; p=0.06, respectively]. In conclusion, no statistically significant association was found between M-Mg and C-Mg levels. Given the relatively small number of samples with high M-Mg level, the results of this study may not apply to infants whose mothers are exposed to prolonged maternal MgSO4 administration.