What is the rationale for administering magnesium sulfate in preeclampsia/eclampsia management?

• A. Prevention of seizures in the mother and neuroprotection for the preterm fetus
• B. Lowering blood pressure
• C. Relieving pain during labor
• D. Promoting fetal lung maturity

Answer: (A)

The key idea is that magnesium sulfate is used to prevent seizures and protect the fetus when preeclampsia/eclampsia is involved. It raises the mother’s seizure threshold by dampening central nervous system excitability, acting as an anticonvulsant to stop progression to an eclamptic seizure. Because the fetus may be preterm, magnesium crosses the placenta and provides neuroprotection, helping reduce the risk of cerebral injury and later motor problems like cerebral palsy in the preterm infant.

This is different from other measures: lowering blood pressure is achieved with antihypertensives, not mainly by magnesium; analgesia is not the purpose here; and fetal lung maturity is boosted by corticosteroids, not magnesium. While magnesium may have minor tocolytic effects in some contexts, its primary role in this setting is seizure prevention and fetal neuroprotection. Monitor for signs of toxicity (loss of reflexes, respiratory depression, reduced urine output) and have calcium gluconate available as an antidote.