Several large clinical studies and a meta-analysis (Crowther, Hiller, Doyle, Haslam, & Australasian Collaborative Trial of Magnesium Sulphate Collaborative, 2003; Doyle, Crowther, Middleton, Marret, & Rouse, 2009; Marret, Doyle, Crowther, & Middleton, 2007; Rouse et al., 2008) have evaluated the evidence regarding magnesium sulfate and fetal neuroprotection and suggest that pre-delivery administration of magnesium sulfate reduces the occurrence of cerebral palsy when given with neuroprotective intent. Magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks’ gestation. (ACOG, 2012)

Recommendations

  • Women with preterm labor, preterm PROM, or fetal indication for delivery at 23 to 31 wks 6 days gestation should receive magnesium sulfate for fetal neuroprotection.
  • Exclusions: evidence of renal insufficiency or other medical conditions (e.g. myasthenia gravis) for which magnesium sulfate would be contraindicated.

Recommended Treatment Protocol

**Based on the US NICHD RCT(Rouse et al., 2008)

  •  Magnesium Sulfate: 6-gram loading dose over 20 minutes then 2 grams per hour for at least 12 hours (or until delivery). After 12 hours, unless delivery is anticipated, the infusion should be stopped.

Retreatment

  • Retreatment is given any time labor recurs or delivery is anticipated except:
  • Deterioration in maternal or fetal status contraindicating the delay in delivery necessary for retreatment
  • Gestational age is greater than or equal to 32 weeks 0 days
  • Magnesium sulfate: 6-gram loading dose over 20 minutes followed by 2 grams/hour.  If the previous infusion was discontinued within six hours of retreatment, skip the 6-gram loading dose and start the infusion at 2 grams per hour.

 

In June 2013, the FDA changed the classification of magnesium sulfate injection from Category A to Category D based on a small number of neonatal cases of osteopenia with prolonged, continuous MgSO4 exposure (>7 days). ACOG and the Society for Maternal-Fetal Medicine continue to support the use of magnesium sulfate in obstetric care for appropriate conditions and for appropriate, short term (usually less than 48 hours) durations of treatment.(ACOG, 2013)

References

ACOG. (2012). Management of Preterm Labor Practice Bulletin 127. [Practice Bulletin No. 127]. The American College of Obstetricians and Gynecologists.

ACOG. (2013). ACOG's Committee on Obstetric Practice and the Society for Maternal-Fetal Medicine continue to support the use of magnesium sulfate in obstetric care.  Retrieved 6/13/2013, 2013, from http://www.acog.org/About_ACOG/Announcements/Magnesium_Sulfate_Category

Crowther, C. A., Hiller, J. E., Doyle, L. W., Haslam, R. R., & Australasian Collaborative Trial of Magnesium Sulphate Collaborative, G. (2003). Effect of magnesium sulfate given for neuroprotection before preterm birth: a randomized controlled trial. JAMA, 290(20), 2669-2676. doi: 10.1001/jama.290.20.2669

Doyle, L. W., Crowther, C. A., Middleton, P., Marret, S., & Rouse, D. (2009). Magnesium sulphate for women at risk of preterm birth for neuroprotection of the fetus. Cochrane Database Syst Rev(1), CD004661. doi: 10.1002/14651858.CD004661.pub3

Marret, S., Doyle, L. W., Crowther, C. A., & Middleton, P. (2007). Antenatal magnesium sulphate neuroprotection in the preterm infant. Semin Fetal Neonatal Med, 12(4), 311-317. doi: 10.1016/j.siny.2007.04.001

Rouse, D. J., Hirtz, D. G., Thom, E., Varner, M. W., Spong, C. Y., Mercer, B. M., . . . Eunice Kennedy Shriver, N. M.-F. M. U. N. (2008). A randomized, controlled trial of magnesium sulfate for the prevention of cerebral palsy. N Engl J Med, 359(9), 895-905. doi: 10.1056/NEJMoa0801187

OB Management

  • Women with preterm labor, preterm PROM, or fetal indications for delivery at 23 to 31 weeks and 6 days gestation should receive magnesium sulfate for fetal neuroprotection.
  • Exclusions: evidence of renal insufficiency or other medical conditions (e.g. myasthenia gravis) for which magnesium sulfate would be contraindicated.

Recommended Treatment Protocol

  • Magnesium Sulfate: 6-gram loading dose over 20 minutes then 2-grams per hour for at least 12 hours (or until delivery). After 12 hours, unless delivery is anticipated, the infusion should be stopped.

 

In June 2013, the FDA changed the classification of magnesium sulfate injection from Category A to Category D based on a small number of neonatal cases of osteopenia with prolonged, continuous MgSO4 exposure (>7 days). ACOG and the Society for Maternal-Fetal Medicine continue to support the use of magnesium sulfate in obstetric care for appropriate conditions and for appropriate, short term (usually less than 48 hours) durations of treatment.(ACOG, 2013)

Re-treatment

  • Retreatment is given any time labor recurs or delivery is anticipated except:
    • Deterioration in maternal or fetal status contraindicating the delay in delivery necessary for re-treatment.
    • Gestational age is ≥ 32 weeks 0 days.
  • Magnesium sulfate: 6-gram laoding dose over 20 minutes followed by 2-grams per hour. If the previous infusion was discontinued within 6 hours of re-treatment, skip the 6-gram loading dose and start the infusion at 2-grams per hour.

In June 2013, the FDA changed the classification of magnesium sulfate injection from Category A to Category D based on a small number of neonatal cases of osteopenia with prolonged, continuous MgSO4 exposure (>7 days). ACOG and the Society for Maternal-Fetal Medicine continue to support the use of magnesium sulfate in obstetric care for appropriate conditions and for appropriate, short term (usually less than 48 hours) durations of treatment.(ACOG, 2013)