Does exposure to magnesium sulfate in utero decrease the risk of necrotizing enterocolitis in premature infants?

Background. The objective of this study is to assess whether antenatal exposure to magnesium sulfate may decrease the risk of necrotizing enterocolitis in preterm infants. Methods. We have compared the rate of magnesium sulfate exposure before birth among 23 consecutive infants diagnosed with necrotizing enterocolitis with that of 46 controls matched by gestational age at delivery and gender. Relevant obstetric and neonatal variables were compared between the two groups using chi-square and Fisher's exact test for categorical data, and one-way analysis of variance for continuous variables, with a two-tailed p-value <0.05 considered significant. Results. No significant differences were present between the two groups in mode of delivery (p= 0.9), rate of Apgar score at five minutes below seven (p= 0.4), prenatal exposure to indocin (p=0.5) or steroids (p=0.6), or neonatal administration of surfactant (p=0.1). Similar proportions of babies with necrotizing enterocolitis and controls were diagnosed with respiratory distress syndrome (p=0.5), intraventricular hemorrhage grades three or four (p=0.9), and sepsis (p=0.6). Babies with necrotizing enterocolitis had a significantly longer hospital stay (74.6±64.0 vs. 41.9±37.0 days, p=0.01) and intubation period (31.4±24.1 vs. 16.8±15.6 days, p=0.01) than controls. The rates of prenatal exposure to magnesium sulfate were similar in the necrotizing enterocolitis and control groups (30% vs. 39% respectively, p=0.4). Power analysis demonstrated that 385 babies would be required in each group to reach statistical significance (α=0.05, β=80%). Conclusion. In this retrospective case-control study, maternal administration of magnesium sulfate prior to delivery does not appear to confer a significant protective effect for the neonatal occurrence of necrotizing enterocolitis.