MgSO4 is the drug of choice for severe preeclampsia and eclampsia. Mechanism of action: It reduces motor endplate sensitivity to acetylcholine and thereby reduces neuromuscular irritability. It also blocks neuronal calcium influx. It induces cerebral vasodilatation, dilates uterine aeries, increases production of endothelial prostacyclin and inhibits platelet activation. Benefits from other regimens: No detrimental effects on the neonate within therapeutic level. Excellent result with maternal moality of 0.4%. Ref: Textbook of Obstetrics by D.C. Dutta, 6th edition, Page 236.