Effect of magnesium sulfate exposure on term neonates

To compare neonatal intensive care unit and special care unit (NICU) admission rates between term neonates exposed to antenatal magnesium sulfate (MS) and those unexposed.

We performed a retrospective cohort study of all singleton neonates ≥37 weeks born to women with pre-eclampsia from August 2006 to July 2008. Cases were defined by antenatal exposure to MS and controls by absence of MS exposure. The primary outcome was NICU admission. Data were analyzed via univariable and multivariable regression analyses.

In all, 28 (14.7%) out of 190 MS-exposed neonates ≥37 weeks were admitted to the NICU, compared with 4 (5.4%) of 74 non-exposed neonates (P=0.04). This association persisted after controlling for potential confounding variables including severe pre-eclampsia and cesarean delivery (AOR 3.69, 1.13 to 11.99). NICU admission was associated in a dose-dependent relationship with total hours and mean dose of MS exposure. Number needed to harm with MS was 11 per NICU admission. Among neonates admitted to the NICU, MS-exposed were more likely to require fluid and nutritional support than unexposed neonates (60.7 vs 0%, P=0.04), and trended toward more frequent requirement for respiratory support and greater length of stay.

In term neonates, MS exposure may be associated independently with NICU admission in a dose-dependent relationship. Requirements for fluid and nutritional support are common in this group, likely due to feeding difficulties in exposed neonates. Assessment of acute care needs among all neonates exposed to MS for maternal eclampsia prophylaxis should be considered.