The possible role of magnesium in protection of premature infants from neurological syndromes and visual impairments and a review of survival of magnesium-exposed premature infants

The survival rate of very preterm, low birth weight infants (weighing less than 1500 g) is 85 per cent in the USA and is ever increasing, while 42 to 75 per cent of extremely premature infants (weighing 751-1000 g) survive. O f great concern is the lack of consistent decrease in neurological syndrome s and associated visual impairments. Because of short gestations, these inf ants have not had time to accrue up to 80 per cent of magnesium normally pr esent at term. These very preterm infants are at highest risk for cerebral hypolda/ischemia (H/I), intracranial hemorrhage (ICH), periventricular leuk omalacia (PVL) or cystic PVL (CPVL). and possible sequelae, cerebral palsy (CP) and mental retardation (MR). These syndromes are associated with damag e to optic structures and the visual pathways which traverse the brain. Vis ual defects are common in surviving preterm infants. Increased levels of ha rmful neurochemical mediators that have been reported in these conditions i nclude oxygen free radicals, excitatory amino acids, tumor necrosis factor- alpha (TNF-a), and thromboxane A(2) (TXA(2)) which are aggravated in magnes ium deficiency and may be ameliorated by magnesium. We review the published data concerning the effects of prenatal magnesium supplementation on ICH, CPVL,CP and MR and available reports concerning survival. Further considera tions on the safety and efficacy of magnesium sulphate administration given prenatally to the preterm neonate await the outcome of three trials that a re continuing for more than a year on three continents.