Serum magnesium levels in neonates born to mothers who received magnesium sulphate during labour at Kenyatta National Hospital

Abstract

Background: Magnesium sulphate administered to the mother parenterally is transported actively through the placenta to achieve equilibrium in fetal serum. It takes about 2 hrs for the maternal and fetal plasma levels to reach equilibrium. Neonatal serum magnesium concentration remains elevated for the first 72 hrs of life. Neonates whose mothers receive magnesium sulphate during labour have been found to have high serum magnesium levels, a lower Apgar score and respiratory depression. Objectives: To determine the serum magnesium levels in neonates born of mothers who received Magnesium sulphate at K.N.H during labour, to document the clinical effects, if any, in the neonates and to relate the levels of serum magnesium to the observed clinical signs in the neonates. Methodology: This was a quasi-experimental study, conducted at Kenyatta National Hospital New Born Unit and Post natal wards. The study subjects were 49 neonates, matched for gestational age with 49 controls. Neonates born of mothers with severe pre-eclampsia/Eclampsia who received magnesium sulphate during labour were recruited as exposed study subjects .The controls were neonates of mothers who had mild pre-eclampsia and so did not receive magnesium sulphate. Sampling of consecutive neonates was done until the required sample size was attained. Serum magnesium and calcium were measured on a semi-automated analyzer (Humalyzer) using commercial reagents. Data Analysis: A standard data collection form was used to collect all the data which was analyzed using the SPSS version 12. Independent sample t-test was used to determine whether the mean serum magnesium differed significantly in the magnesium exposed and non-exposed neonates. P values below 0.05 were considered significant. x Results There were 49 neonates in each arm of the study. The two groups were comparable in terms of birth weight and gestational age. Neonates whose mothers received magnesium sulphate were found to have higher serum magnesium levels than those whose mothers did not, with mean serum magnesium levels of 2.22mmolll and 1.22mmolll respectively, p=<O.OO1.All the 49 (100%) study subjects had magnesium levels >1.04 mmolll compared to 22 (44.9%) controls .The study subjects were also more likely to have depressed neonatal reflexes than the controls but the difference was not stastically significant, P'=O.297. The study subjects were found to have a lower Apgar score at both one and five minutes when compared with the controls. The mean score at Iminute was 6.8 and 7.5 for study subjects and controls respectively (p=0.019) while at 5 minutes it was 8.1 and 8.9, respectively. p=0.010. Conclusions Neonates whose mothers received magnesium sulphate had higher than normal serum magnesium levels and were also found to have lower Apgar scores than the controls. Recommendations Close monitoring of neonates whose mothers receive magnesium sulphate during labour is recommended. Further research that will follow up the neonates for a longer period to establish the pattern of morbidity and mortality and determine whether it is associated with the serum magnesium levels III the neonates is recommended