Yes, seizures are the defining feature of eclampsia. Eclampsia is not a condition that sometimes leads to seizures; it is, by definition, the onset of seizures in a pregnant or recently pregnant person with a hypertensive disorder. If there are no seizures, it isn’t eclampsia. The condition is a life-threatening pregnancy complication responsible for an estimated 11% to 14% of maternal deaths worldwide.
What Eclamptic Seizures Look Like
Eclamptic seizures can be tonic-clonic (the full-body convulsions most people picture), focal (affecting one part of the body), or multifocal (affecting several areas). Tonic-clonic seizures are the most common type. Most are self-limiting, meaning they stop on their own within a few minutes without intervention. That doesn’t make them safe. Even a single seizure carries serious risks, including loss of consciousness, injury from falling, aspiration, and reduced oxygen supply to both the mother and baby.
These seizures can strike before labor, during delivery, or after the baby is born. A significant number happen in the postpartum period, sometimes days after delivery. Research on postpartum eclampsia found that 79% of late-onset cases occurred more than 48 hours after delivery, and late postpartum eclampsia can happen up to six weeks after birth. This surprises many people who assume the risk disappears once the baby arrives.
Why Eclampsia Causes Seizures
Eclampsia develops from preeclampsia, a condition defined by dangerously high blood pressure (140/90 mm Hg or higher after 20 weeks of pregnancy) combined with signs of organ damage, such as protein in the urine, abnormal liver or kidney function, or low platelet counts. When preeclampsia becomes severe enough to affect brain function, it crosses the threshold into eclampsia.
The underlying problem is vascular. In preeclampsia, blood vessels throughout the body behave abnormally, constricting and becoming more permeable. In the brain, this means blood vessels can spasm, disrupting normal blood flow, and the barrier that normally keeps fluid out of brain tissue starts to break down. The result is swelling in the brain, which irritates nerve cells and triggers seizure activity. This is why controlling blood pressure and preventing brain swelling are central to treatment.
Warning Signs Before a Seizure
Eclamptic seizures rarely arrive without warning. The progression from preeclampsia to eclampsia typically produces recognizable symptoms, though they can escalate quickly. The most common warning signs include:
- Severe headache that doesn’t respond to usual pain relief
- Vision changes such as blurred vision, seeing spots, or temporary blindness
- Upper abdominal pain, particularly on the right side under the ribs
- Nausea and vomiting that appear suddenly, especially in the third trimester or postpartum
- Decreased urine output
A study of women who arrived at emergency rooms with postpartum preeclampsia found that headache, vision changes, and nausea or abdominal pain were the most frequent complaints. These symptoms reflect the strain on the brain, liver, and kidneys. Any combination of these in a pregnant or recently pregnant person with high blood pressure is a medical emergency.
How Eclamptic Seizures Are Treated
Magnesium sulfate is the primary treatment, and it has been the standard of care for decades. Its main purpose is preventing additional seizures rather than stopping one already in progress. In a large multinational trial, magnesium sulfate reduced the risk of recurrent seizures by 52% compared to one alternative and 67% compared to another. It works partly by stabilizing nerve cells in the brain, making them less likely to fire abnormally.
Beyond seizure prevention, treatment focuses on controlling blood pressure and, in many cases, delivering the baby. Delivery is the only definitive treatment for the underlying condition. The timing depends on how far along the pregnancy is and how severe the situation has become. After delivery, close monitoring continues because seizures can still occur days or even weeks later.
Distinguishing Eclampsia From Other Seizure Causes
Not every seizure during pregnancy is eclampsia. Epilepsy, stroke, infections, and other neurological conditions can also cause seizures in pregnant people. Clinicians distinguish eclampsia from these other causes by looking for the hallmarks of preeclampsia: high blood pressure, organ damage markers in blood work, and the characteristic timing (after 20 weeks of pregnancy or in the postpartum period). A diagnosis of eclampsia specifically requires that no other neurological explanation accounts for the seizure.
This distinction matters because the treatments are different. A person with epilepsy who has a seizure during pregnancy needs their existing seizure medications managed. A person with eclampsia needs magnesium sulfate, blood pressure control, and often delivery. Getting the diagnosis right requires careful evaluation and sometimes input from multiple specialists.
The Stakes of Eclampsia
Globally, hypertensive disorders of pregnancy, including eclampsia, are the second most common direct cause of maternal death. The risk is dramatically higher in low- and middle-income countries, where 10% to 15% of direct maternal deaths are linked to preeclampsia and eclampsia. In high-income countries, outcomes are generally better due to earlier detection and faster access to treatment, but eclampsia remains dangerous everywhere.
One complication that significantly worsens outcomes is HELLP syndrome, a severe form of preeclampsia involving the breakdown of red blood cells, elevated liver enzymes, and low platelets. Among women who die from eclampsia in high-income countries, roughly 90% also have HELLP syndrome. In low-income countries, that figure drops to about 48%, largely because other factors like delayed access to care account for more deaths before HELLP has time to develop.
The risk to the baby is also substantial. Reduced blood flow through the placenta, premature delivery necessitated by the mother’s condition, and oxygen deprivation during maternal seizures all contribute to complications ranging from low birth weight to stillbirth.