A nurse is caring for a client who has preeclampsia and is being treated with magnesium sulfate IV. The client's respiratory rate is 10/min and deep-tendon reflexes are absent. Which of the following actions should the nurse take?

A. Maternal blood glucose assessment is unrelated to magnesium sulfate toxicity and would not address the immediate life-threatening issue. B. Discontinuing magnesium sulfate is the priority because the client is showing signs of magnesium toxicity—respiratory depression and absent deep-tendon reflexes. Immediate cessation of the infusion prevents further complications. The nurse should also notify the provider and be prepared to administer calcium gluconate, the antidote for magnesium toxicity. C. Preparing for cesarean birth may be necessary depending on maternal-fetal status, but the immediate threat is respiratory compromise from toxicity, which takes precedence. D. Trendelenburg position does not correct magnesium toxicity and is not indicated; respiratory support and stopping the infusion are urgent priorities.