The newborn of a mother on magnesium sulfate therapy would NOT be expected to show which finding?

• A. Hypotension
• B. Hypoglycemia
• C. Hyperreflexia
• D. Respiratory depression

Answer: (C)

Magnesium sulfate crosses the placenta and acts as a CNS depressant in the fetus, lowering neuromuscular excitability. In the newborn, this typically manifests as decreased reflexes (hyporeflexia), reduced muscle tone (hypotonia), and possible respiratory depression due to diminished respiratory drive. Because of this depressant effect, exaggerated reflexes would not be expected. The other possibilities align with the baby being impacted by the drug's CNS and neuromuscular effects: respiratory depression can occur, and changes in tone or reflexes are common. Hypotension can be seen in the context of magnesium exposure as well, though it’s more characteristically a maternal effect; neonatal hypoglycemia is not a direct, typical consequence of maternal magnesium sulfate exposure.