Magnesium sulfate has been widely used in obstetric care for prevention and treatment of seizures in preeclampsia and eclampsia as well as a tocolytic (despite the lack of efficacy in this treatment) for many years (Doyle, Crowther, Middleton, Marret, & Rouse, 2009). In the late 1980s and 1990s, researchers began to notice that rates of intraventricular hemorrhage and cerebral palsy (CP) were lower among children who had been exposed to magnesium sulfate in utero (Salmeen, Jelin, & Thiet, 2014). Since this discovery, there have been several randomized controlled trials (RCTs) showing efficacy of magnesium sulfate for neuroprotection in preterm infants. Their results support routine use of magnesium sulfate for infant neuroprotection for women at risk for early preterm birth (less than 32 weeks gestation) (American College of Obstetricians and Gynecologists [ACOG] & Society for Maternal-Fetal Medicine [SMFM], 2010; Doyle et al.; Salmeen et al.). There is a dramatically higher incidence of CP in preterm and low-birthweight infants (Salmeen et al.), so this population could benefit most.

Although there is general agreement that this is a worthwhile CP prevention strategy with relatively low risk to the mother (ACOG & SMFM, 2010; Doyle et al., 2009), an optimal treatment regimen has not been established (Bain, Middleton, & Crowther, 2012). The decreased rates of CP among babies of mothers who had received magnesium sulfate were first observed incidentally in studies where the medication was used for seizure prophylaxis or tocolyis; therefore, the dosing regimens used in these studies were what the RCTs evaluated for neuroprotection (Bain et al.). In two large RCTs of intravenous magnesium sulfate, one used a 4 g loading dose over 20 minutes with 1 g/hour as maintenance for up to 24 hours with no redosing, whereas the other used a 6 g load over 20 to 30 minutes with 2 g/hour as maintenance, stopped at 12 hours if birth had not occurred, and could be redosed once (Bain et al.). Due to the lack of a significant difference in outcomes between the two regimens, there is still no clearly superior dosing regimen. Some have suggested the lower dose regimen may be safest and has the least side effects (Bain et al.). However, provider comfort and institutional familiarity with a certain dosing regimen could be a factor in which regime is safest in each hospital. When administering magnesium sulfate for neuroprotection, ACOG and SMFM (2010) recommend development of specific guidelines including appropriate candidates, dosing regimens, and monitoring. A patient safety checklist offered by ACOG (2012) may be helpful in promoting safe care during magnesium sulfate administration.

More research is needed to determine the most conservative optimal dosing to produce adequate neuroprotection and outcomes. In the interim, a dosing regime from one of the larger RCTs as outlined in the ACOG patient safety checklist is appropriate (ACOG, 2012; ACOG & SMFM, 2010). Although babies born at term are also at risk for CP, there is no evidence that routine use of magnesium sulfate in high-risk term infants will prevent CP (Salmeen et al., 2014), so magnesium sulfate administration is not recommended for women with term at-risk pregnancies.

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