Reference — Maternal-Newborn
Magnesium Sulfate Reference
One drug, two obstetric jobs — eclamptic seizure prevention and preterm fetal neuroprotection — with the same monitoring, the same toxicity ladder, and the same antidote at the bedside.
Educational use only. Magnesium is a high-alert medication run by pump under protocol — doses, levels, and hold criteria here are common conventions, not orders. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Indications & Dosing Conventions
Seizure prophylaxis in preeclampsia with severe features and treatment of eclampsia — commonly a 4–6 g IV load over 20–30 minutes, then 1–2 g/hr maintenance, typically continued 24 hours after delivery or the last seizure.
Fetal neuroprotection before ~32 weeks when preterm delivery is anticipated — reduces cerebral palsy risk; protocols vary on load and duration.
Always by infusion pump, always with a second-nurse check per high-alert policy, and always with calcium gluconate immediately available.
The Monitoring Trio (Plus Two)
| Parameter | Target | Red Flag |
|---|---|---|
| Deep tendon reflexes | Present (e.g., patellar 1–2+) | Absent reflexes — the earliest toxicity warning |
| Respiratory rate | ≥12/min | Below 12, or rising somnolence |
| Urine output | ≥30 mL/hr | Oliguria — magnesium is renally cleared; toxicity follows low output |
| Fetal heart rate | Reassuring tracing | Decreased variability is expected on magnesium; decelerations are not |
| Serum magnesium (per order) | Commonly ~4–7 mEq/L therapeutic | Rising level with clinical signs |
The Toxicity Ladder
| Stage | Findings | Nursing Action |
|---|---|---|
| Therapeutic effect | Reduced CNS irritability; flushing, warmth, mild lethargy expected | Continue per protocol; hourly monitoring |
| Early toxicity | Deep tendon reflexes diminish, then disappear | Stop the infusion; notify the provider; draw a level per order |
| Progressing toxicity | Respiratory depression (commonly flagged <12/min); somnolence; slurred speech | Infusion off; support airway and breathing; calcium gluconate per order |
| Severe toxicity | Respiratory arrest; cardiac conduction changes → arrest | Emergency response; calcium gluconate IV; full resuscitation |
The order is the lesson: reflexes go first, breathing second, the heart last. Acting at the reflex stage is what keeps the rest of the ladder theoretical.
The Antidote
Calcium gluconate (commonly 1 g IV over several minutes per protocol) reverses magnesium’s neuromuscular and cardiac depression. It lives at the bedside — in the room, not in the Pyxis — for every magnesium infusion.
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with American College of Obstetricians and Gynecologists (ACOG) · AWHONN · American Academy of Pediatrics (AAP) — newborn. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →