Magnesium sulfate tocolysis and intraventricular hemorrhage in very preterm infants

To estimate the contributory effect of tocolytic magnesium sulfate (MgSO4) exposure to intraventricular hemorrhage (IVH) in preterm infants born at 23-31 wks gestation to mothers without evidence of pregnancy induced hypertension and/or preeclampsia.

Cases with IVH and controls without IVH were selected from a population-based cohort of preterm infants admitted from January 2004 through May 2008 to the Level III Neonatal Intensive Care Unit (NICU) at Robert Wood Johnson University Hospital. Cases and controls were matched primarily by exact gestational age in completed weeks and secondarily by the birth weight that was same or similar (+/-100 g). The odds of tocolytic MgSO(4) exposure among the cases and controls was tested in a regression model to control the difference in demographic and clinical factors between the IVH cases (IVH+) and controls without IVH (IVH-).

Eighty-nine IVH cases and 89 controls were comparable for parity, mode of delivery, antenatal corticosteroid exposure, and surfactant administration. IVH cases were less likely to have preterm premature rupture of membranes and were more likely to be born with low Apgar scores and require ventilation. Among the IVH cases, 30.3% of infants were exposed to tocolytic MgSO4 as compared to 47.2% of controls (Odds Ratio adjusted 0.471, 95% Confidence Interval 0.241, 0.906).

Among the preterm born infants with gestational age 23-31 wks and IVH, tocolytic MgSO4 exposure was less likely to be observed than in neonates with similar clinical characteristics but without IVH, thereby suggesting that antenatal exposure to MgSO(4) may have a protective effect against IVH.