In whom should magnesium sulfate be given for fetal neuroprotection?

Magnesium Sulfate for Fetal Neuroprotection

Magnesium sulfate should be administered for fetal neuroprotection when preterm delivery is anticipated before 32 weeks' gestation, as it significantly reduces the risk of cerebral palsy without increasing mortality. 1, 2

Indications Based on Gestational Age

• Before 32 weeks' gestation: Magnesium sulfate is strongly recommended for fetal neuroprotection when preterm delivery is anticipated 3, 1, 2
• Periviable period (23-25 weeks): Magnesium sulfate prophylaxis is recommended if delivery of a potentially viable infant is anticipated 3, 4
• Before 23 weeks' gestation: Magnesium sulfate is not recommended for neuroprotection 4

Special Clinical Scenarios

• Fetal growth restriction:

  • In cases with absent end-diastolic flow, when delivery is considered by 34 weeks, magnesium sulfate should be administered if delivery occurs before 32 weeks 3, 1
  • In cases with reversed end-diastolic flow, when delivery is considered by 30 weeks, magnesium sulfate should be administered 3, 1

• Premature rupture of membranes (PROM):

  • Magnesium sulfate should be administered concurrently with appropriate antibiotic therapy when delivery is anticipated before 32 weeks 4
  • Administration should not begin until the time when neonatal resuscitation and intensive care would be considered appropriate by the healthcare team and desired by the patient 4

• Preeclampsia: Magnesium sulfate serves dual purposes - prevention of eclamptic seizures and fetal neuroprotection 1

Evidence of Benefit

• Magnesium sulfate reduces cerebral palsy (RR 0.71,95% CI 0.57 to 0.89) and death or cerebral palsy (RR 0.87,95% CI 0.77 to 0.98) in children up to two years' corrected age 5
• It probably reduces severe intraventricular hemorrhage (grade 3 or 4) (RR 0.76,95% CI 0.60 to 0.98) 5
• The benefit remains consistent regardless of gestational age, cause of preterm birth, and total dose received 6

Administration Guidelines

• The U.S. Food and Drug Administration supports the short-term (usually less than 48 hours) use of magnesium sulfate for fetal neuroprotection before anticipated early preterm delivery 7
• Magnesium sulfate should not be used as a tocolytic for pregnancy prolongation in PROM cases, but rather specifically for neuroprotection 4
• Magnesium sulfate administration does not impact latency in women with PPROM 8

Safety Considerations

• Monitor neonates exposed to maternal magnesium sulfate for potential hypotonia and respiratory depression after birth 4
• Magnesium sulfate may increase maternal adverse effects severe enough to stop treatment, but serious maternal outcomes (death, cardiac arrest, respiratory arrest) are rare 5
• Premature newborns exposed to maternal magnesium sulfate therapy may have high magnesium levels in the first days of life and require monitoring 1

Concurrent Therapies

• Antenatal corticosteroids should be administered between 24+0 and 34+0 weeks of gestation when preterm delivery is anticipated 3, 1, 4
• Broad-spectrum antibiotics should be administered during expectant management of preterm PROM to prolong pregnancy and reduce newborn infections 3, 4