Use in Pregnancy: Magnesium Sulfate is administered to pregnant women to treat seizures associated with severe pre-eclampsia and eclampsia. Magnesium Sulfate readily crosses the placenta. Fetal serum concentrations approximate those of the mother. If Magnesium Sulfate is administered in the two hours preceding delivery, the neonate may be born with signs of hypermagnesemia, including respiratory depression, and therefore Magnesium Sulfate Injection should not be given in the two hours preceding delivery unless it is the only therapy available to prevent or treat eclamptic seizures. Bony abnormalities and congenital rickets have been reported in neonates born mother treated with parenteral Magnesium Sulfate for prolonged periods of time (4 - 13 weeks duration).
Use in Lactation: After intravenous administration, Magnesium is distributed into breast milk, and the concentration of Magnesium in the breast milk is approximately twice that in the maternal serum. Magnesium salts should therefore be used with caution in lactating patients. However, Magnesium is cleared from the breast milk within 24 hour of the cessation of the infusion.