Effects of Maternal Magnesium Sulfate Treatment on Neonatal Feeding Tolerance

To determine whether antenatal exposure to magnesium sulfate has an effect on neonatal enteral feeding tolerance.

In this single-center, retrospective, observational study, charts of pregnant women who received intravenous magnesium sulfate infusions prior to delivery between July 1, 2012, and July 31, 2013, were reviewed. Neonates born at 24 weeks' gestational age or greater admitted to the neonatal intensive care unit (NICU) whose mothers received magnesium sulfate infusions prior to delivery were included. Neonates with independent factors that could lead to feeding intolerance were excluded. The primary outcome was incidence of neonatal enteral feeding intolerance measured by deviations from the NICU feeding protocol. Secondary outcomes included days on parenteral nutrition, incidence of necrotizing enterocolitis, time to first stool, and urine output in the first 72 hours of life.

Cumulative maternal magnesium sulfate dose was significantly higher in the enteral feeding intolerance group than those infants who tolerated enteral feeds (70.4 ± 52.3 vs 47.4 ± 40.1 g; p = 0.04). Infants exposed to more than 80 g of maternal magnesium sulfate therapy were more likely to develop enteral feeding intolerance (44% vs 22%; p = 0.04). Multivariate logistic regression indicated that prematurity and cumulative maternal magnesium sulfate dose were the strongest predictors of neonatal enteral feeding intolerance.

Infants of mothers who received more than 80 g of intravenous magnesium sulfate prior to delivery were more likely to develop feeding intolerance. Prematurity also was a significant predictor of intolerance.