Eclampsia is a serious pregnancy complication in which a woman develops seizures, typically as a progression of preeclampsia (a condition marked by high blood pressure during pregnancy). It affects roughly 0.4% of pregnancies globally, though rates vary dramatically by region. In high-income countries like Denmark, the rate drops to about 0.03%, while in parts of South Asia and sub-Saharan Africa it can exceed 1 to 2%. The difference comes down to access to prenatal care and early detection of the warning signs that precede it.
How Preeclampsia Becomes Eclampsia
Eclampsia doesn’t appear out of nowhere. It develops from preeclampsia, a condition where blood pressure rises abnormally during pregnancy and damages blood vessels throughout the body. The seizures happen when that damage reaches the brain.
The leading explanation centers on two related problems. First, the brain has a built-in system for regulating its own blood flow. When blood pressure spikes, blood vessels in the brain normally constrict to keep flow steady. In eclampsia, that system fails. The surge of high-pressure blood pushes past the brain’s defenses, damaging tiny blood vessels. Second, this damage breaks down the blood-brain barrier, the tightly sealed lining of brain capillaries that normally keeps fluids and proteins out of brain tissue. Once that barrier leaks, fluid seeps into the surrounding brain tissue, causing swelling (called vasogenic edema), inflammation, and ultimately seizures.
Circulating substances released during preeclampsia, including inflammatory molecules and oxidized cholesterol particles, appear to make the blood-brain barrier even more vulnerable through oxidative stress. This helps explain why some women with moderately elevated blood pressure still develop seizures: it’s not just the pressure itself, but the broader vascular damage of preeclampsia weakening the brain’s protective systems.
Warning Signs Before a Seizure
Most women experience recognizable symptoms before an eclamptic seizure strikes. In one study of 46 eclampsia cases, 80% of women reported headaches beforehand, and 45% had visual disturbances such as blurred vision, seeing spots, or sensitivity to light. These neurological symptoms were the most common warning signs regardless of how high blood pressure was or whether the seizure happened before or after delivery.
That said, about 17 to 20% of women who developed eclampsia reported no warning symptoms at all. This is part of what makes the condition dangerous: while most cases announce themselves, a meaningful minority do not. Routine blood pressure monitoring and urine testing during prenatal visits exist specifically to catch preeclampsia before it has a chance to progress silently.
When Eclampsia Can Occur
Eclampsia can develop at three different points: before labor, during labor, or after delivery. About 40% of seizures happen before delivery begins. The rest occur during or after birth, and roughly 16% happen more than 48 hours postpartum. This means the risk doesn’t end the moment a baby is born. Postpartum eclampsia can catch families off guard, since many assume the danger passes with delivery. New mothers experiencing severe headaches, vision changes, or sudden swelling in the days after giving birth need immediate medical evaluation.
Who Is at Higher Risk
Because eclampsia grows out of preeclampsia, the risk factors overlap heavily. The strongest predictor is a history of preeclampsia in a previous pregnancy, which raises the risk roughly eightfold. Chronic high blood pressure before pregnancy is the second most significant factor, associated with about five times the usual risk.
Other well-established risk factors include:
- First pregnancy (nulliparity): Women who have never given birth before face higher risk than those who have.
- Pre-existing diabetes (type 1 or type 2): Associated with about 3.7 times the risk, with roughly 11% of diabetic pregnancies developing preeclampsia.
- BMI over 30 before pregnancy: Nearly triples the risk, with about 7% of these pregnancies progressing to preeclampsia.
- Antiphospholipid antibody syndrome: An autoimmune clotting disorder that carries the highest rate of preeclampsia of any single risk factor, at about 17%.
- Chronic kidney disease or lupus: Both independently increase risk.
- Pregnancies conceived through assisted reproduction (IVF): About 6% develop preeclampsia, nearly double the baseline rate.
- Carrying multiples: Twin or triplet pregnancies put extra strain on the cardiovascular system.
- Advanced maternal age: Older mothers face progressively higher odds.
Women with several of these factors are often candidates for low-dose aspirin during pregnancy, which can reduce the likelihood of preeclampsia developing in the first place.
Complications for Mother and Baby
Eclampsia puts both lives at immediate risk. For the mother, the seizures themselves can cause injury, aspiration, or oxygen deprivation. But the underlying vascular damage creates additional threats. In one study of women hospitalized with severe preeclampsia and eclampsia, 39.5% developed HELLP syndrome, a dangerous breakdown of red blood cells combined with liver damage and low platelet counts. Placental abruption, where the placenta separates from the uterine wall before delivery, occurred in 27.3% of cases.
For the baby, the risks stem from reduced blood flow through the damaged placenta and from the need for early delivery. Many eclampsia cases occur before the baby has reached full term, meaning prematurity and its associated complications are common.
How Eclampsia Is Treated
The immediate priority during an eclamptic seizure is stopping it and preventing another one. Magnesium sulfate is the standard treatment worldwide. It’s given intravenously to control seizures and is continued as a maintenance infusion afterward to prevent recurrence. This has been the cornerstone of eclampsia treatment for decades and remains more effective for this specific type of seizure than traditional anti-seizure medications.
The definitive treatment, though, is delivery. Eclampsia will not fully resolve while the pregnancy continues. Once a woman’s condition is stabilized after a seizure, the medical team moves toward delivering the baby. Cesarean section is the most common approach, recommended after stabilization in most cases. Vaginal delivery is only considered in narrow circumstances: when the woman is fully conscious and stable, the baby is doing well on monitoring, the cervix is already favorable for labor, and delivery can be expected within hours. For women who aren’t already in active labor, urgent cesarean section is the standard recommendation.
Long-Term Health After Eclampsia
Recovery from eclampsia doesn’t end with delivery. Women who have had preeclampsia or eclampsia are twice as likely to develop cardiovascular disease and stroke in the 10 to 15 years following the affected pregnancy compared to women whose pregnancies were uncomplicated. This isn’t just a leftover effect of the pregnancy itself. Preeclampsia and heart disease share underlying risk factors, including blood vessel dysfunction and metabolic changes, and the stress of preeclampsia may accelerate damage that was already building.
By their mid-forties, about half of women who had preeclampsia have developed chronic high blood pressure, the single most important risk factor for vascular dementia later in life. Research from the American Heart Association supports early, proactive management of blood pressure and metabolic health (cholesterol, blood sugar, weight) in the years after a preeclamptic or eclamptic pregnancy. A history of eclampsia is, in many ways, an early warning signal about long-term cardiovascular vulnerability, one that gives women and their doctors a meaningful head start on prevention.