Abstract

Background: Antenatal magnesium sulfate can potentially reduce the risk of cerebral palsy in neonates delivered between 24 and 32 weeks of gestational age. Some studies using high-dose magnesium sulfate for neuroprotection have reported increased perinatal mortality.

Methods: A retrospective study was conducted on 475 neonates born between 24 and 32 weeks of gestational age. Serum magnesium level in the first 24 h of life was used to stratify the neonates treated with antenatal magnesium into four subgroups: A (<2.5 mEq/L), B (≥2.5 to <3.5 mEq/L), C (≥3.5 to <4.5 mEq/L), and D (≥4.5 mEq/L). Primary outcome of survival without intraventricular hemorrhage (IVH) and/or periventricular leukomalacia (PVL) along with secondary outcomes, such as Apgar scores, resuscitation, intubation, broncho-pulmonary dysplasia, retinopathy of prematurity (ROP), patent ductus arteriosus (PDA), time to reach full feeds, length of stay (LOS), and mortality during immediate neonatal period were studied.

Results: Of the 475 neonates included in the study, 289 (61%) received antenatal magnesium sulfate. Primary outcome of survival without IVH and/or PVL among the preterm neonates was 70.9% in those receiving and 74.2% in those not receiving antenatal magnesium (P=0.25). There were higher incidences of ROP (P=0.02), PDA (P=0.01), greater time to reach full feeds (P=0.03), and increased LOS (P=0.01) in neonates who had received antenatal magnesium. These findings were not statistically significant when the data were corrected for gestational age and birth weight. Among the subgroups, there was a significantly increased mortality rate (P<0.05) with increasing magnesium levels (5% vs. 16.9%, P<0.05 in groups A vs. D) and a trend toward higher intubation rate (P=0.1) and PDA (P=0.14).

Conclusion: Antenatal magnesium is safe in the immediate postnatal period; however, in the subset of preterm neonates with serum magnesium levels >4.5 mEq/L, there is increased mortality independent of birth weight and gestational age. Identification of these neonates and appropriate dosing for their antenatal neuroprotection needs to be studied.