OB - Managing Severe Preeclampsia. NCLEX example: The nurse cares for an 8-lb, 8-oz newborn. The infant’s history indicates the mother was given magnesium sulfate IV 4 g in 250 mL D5W several hours before delivery. The nurse is MOST concerned if which of the following was observed? A: RR of 18. Rationale: Magnesium Sulfate can cause slowing of respirations and hyporeflexia of newborn. Normal newborn RR 30-60/min.