Correlation of neonatal and maternal serum magnesium levels in pre-eclamptic women

Abstract

Introduction Pre-eclampsia is diagnosed with occurrence of hypertension (moderate to severe) and significant proteinuria (>300mg/24hour urine protein collection) during pregnancy. By the incidence of about 6-8% of all pregnancies, it is considered as one of the commonly encountered serious adverse events during pregnancy. Also, it is associated with maternal and perinatal morbidities as well as mortality. 1-3 Magnesium sulphate (MgSO4) administration for prophylaxis and control of eclamptic convulsions, as an important part of the management strategy, is widely accepted despite the fact that patho-physiologic basis of their occurrence is not completely explained. 2-4 After receiving MgSO4, total and ionized magnesium concentration in maternal serum showed rapid rise within thirty minutes till its plateau state that achieved the required therapeutic levels of 2.0 to 3.5 mmol/L. MgSO4 acts at motor end plates reducing acetylcholine release within the neuromuscular junctions leading to direct vasodilatation. Furthermore, it is considered as a synthetic calcium antagonist. However, magnesium is largely (almost 95%) excreted through well functioning kidneys. 5,6 High magnesium levels could result in serious adverse effects in pre-eclamptic pregnant women depending on its serum levels. Minor ones included nausea, flushing and headache. Life-threatening events were associated with hypermagnesemia (>4.9 mmol/L) such as; muscular disability, hypoventilation, ventricular arrhythmias up to cardiac arrest. Thus, health care providers should be oriented about such complications and their monitoring during MgSO4 administration keeping its antidote, calcium gluconate, always ready. 6 Furthermore, maternal hypermagnesemia was accompanied by high neonatal serum magnesium levels through placental transfer. Moreover, antenatal maternal MgSO4 treatment showed transient hypermagnesemia during the early days of life of infants born to these mothers. 7-11 Levels (>2.5 mmol/L) led to neonatal systemic hypotension, central nervous system (CNS) and respiratory depression. Serum magnesium (>7.4 mmol/L) could lead to complete heart block or asystole. Maternal high magnesium levels also affected fetal calcium metabolism, leading to neonatal hypocalcaemia due to immediate block of calcium placental transfer. If serum calcium reached levels lower than 1.6-1.7 mmol/L in either term or preterm neonates, it would cause wide range of problems such as; neuromuscular irritability up to con…