Nursing care
Preeclampsia vs eclampsia: where the line is and what comes first
Written and reviewed by Amanda Lewis, ADN, RN, BLS · 4 min read · Updated October 2026
Short answer
The dividing line is a seizure. Preeclampsia is new or worsening high blood pressure after 20 weeks of pregnancy with protein in the urine or signs of organ damage. Eclampsia is preeclampsia plus an unexplained generalised seizure. It can occur after birth and without previously severe blood pressure, so warning signs such as severe headache and visual changes matter.
The deciding finding: a generalised seizure
MSD Manuals defines eclampsia as unexplained generalised seizures in a patient with preeclampsia. Everything before that point, however severe, is still preeclampsia. Severe features of preeclampsia include very high blood pressure, low platelets, liver or kidney impairment, pulmonary oedema and neurological symptoms.
The seizure changes the nursing focus from prevention to emergency safety. Progression does not follow a neat ladder: MSD Manuals notes seizures can occur without a prior diagnosis of severe hypertension, and preeclampsia can develop after delivery, within about six weeks. A single normal blood pressure reading does not remove the risk.
Warning signs that come before a seizure
The NHS lists symptoms that need urgent assessment: a severe headache that does not ease with simple painkillers, blurred vision or flashing lights, pain just below the ribs, vomiting, persistent heartburn, sudden swelling of the face, hands or feet, and feeling very unwell. Several of these reflect brain or liver involvement.
Swelling and protein in the urine also occur with normal pregnancy or other conditions, so they cannot show how close a patient is to a seizure. Brisk reflexes and clonus are classic nursing findings in severe preeclampsia, but they are not a reliable predictor. Rising blood pressure with new neurological symptoms needs prompt reporting.
Nursing priorities in preeclampsia: monitoring and magnesium
Magnesium sulfate is given to prevent seizures and to prevent further seizures after eclampsia, usually continuing for a period after birth. It is not the treatment for hypertension, so antihypertensive medicine may be ordered separately. Delivery is the definitive treatment, timed by gestation and the condition of mother and fetus.
The nurse monitors for magnesium toxicity through deep tendon reflexes, respiratory rate, level of consciousness and urine output. Loss of reflexes, slowed breathing or low urine output need immediate reporting, and MSD Manuals names calcium gluconate as the antidote, kept available per protocol. Fetal monitoring, fluid balance and blood pressure checks continue throughout.
Nursing priorities during and after an eclamptic seizure
During a seizure, the nurse stays with the patient, calls for help, protects her from injury, and keeps the airway clear by turning her onto her side, which also takes pressure off the major vessels. Nothing is placed in the mouth. Oxygen and suction are prepared as ordered.
After the seizure, the team gives or continues magnesium sulfate as ordered, controls blood pressure and assesses the fetus. The nurse documents the seizure, checks for injury, watches for aspiration and further seizures, and supports the team's decisions about timing and mode of birth once the mother is stable.
Hypothetical practice scenario
Hypothetical scenario, not a real exam item: a client at 35 weeks with preeclampsia is receiving magnesium sulfate. Her breathing has slowed well below her baseline, patellar reflexes are absent, and urine output over recent hours is low. Which action is first: stop the infusion and notify the provider, document the findings as expected, or increase the rate to prevent seizures?
Stopping the infusion and notifying the provider is correct, because absent reflexes, slowed breathing and low urine output point to magnesium toxicity, and calcium gluconate may be ordered. Documenting as expected misses a dangerous change. Increasing the rate is the tempting distractor: it confuses seizure prevention with safety and would worsen toxicity.
Sources and further reading
MSD Manual Professional Version: Preeclampsia and Eclampsia. Definitions of preeclampsia, severe features and eclampsia, seizures without prior severe hypertension, postpartum onset, magnesium sulfate monitoring, calcium gluconate antidote and delivery as definitive treatment.
NHS: Pre-eclampsia. Warning symptoms needing urgent help, onset from 20 weeks and after birth, and seizures as a serious complication.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our maternity and newborn practice questions are the closest set to what this page covers.
Common questions
Can eclampsia happen after the baby is born?
Yes. The NHS notes preeclampsia can develop in the days or weeks after birth, and MSD Manuals describes onset up to about six weeks postpartum. Postpartum patients with severe headache, visual changes or high blood pressure need urgent assessment.
Does magnesium sulfate lower blood pressure in preeclampsia?
Its main purpose is to prevent seizures, not to treat hypertension. Blood pressure is managed with separate antihypertensive medicine ordered by the provider, while the nurse monitors reflexes, respirations, consciousness and urine output for magnesium toxicity.
Is swelling a reliable sign of worsening preeclampsia?
Not on its own, because swelling is common in normal pregnancy. Sudden swelling of the face, hands or feet is worth reporting, but new headache, visual disturbance, pain under the ribs and rising blood pressure are more concerning warning signs.