Eclampsia is a rare but life-threatening pregnancy complication that causes seizures in women who have or develop high blood pressure during pregnancy. This condition can occur at any point after the 20th week of pregnancy, during labor, or even up to six weeks after giving birth, making it a critical concern for expecting and new mothers alike.

Understanding How Common Eclampsia Really Is

Eclampsia is considered a rare condition, though it remains a significant health concern worldwide. In developed countries like the United States, eclampsia affects between 1 and 10 pregnant women out of every 10,000 deliveries, representing fewer than 1% of pregnant women with high blood pressure during pregnancy.^[1] Globally, eclampsia affects approximately 1.4% of all deliveries.^[7]

The occurrence of eclampsia varies dramatically depending on where women live and the quality of healthcare they can access. In developed nations with advanced medical care systems, eclampsia occurs in about 1 in 2,000 deliveries. However, in developing countries where access to prenatal care may be limited, the condition can affect women 10 to 30 times more frequently.^[7] This stark difference highlights how proper monitoring and early intervention can dramatically reduce the risk of this dangerous complication.

Despite being rare, eclampsia contributes significantly to maternal mortality worldwide. Maternal mortality, which refers to death during pregnancy or shortly after childbirth, occurs in approximately 0 to 1.8% of eclampsia cases in high-income countries. In low- to middle-income countries, this rate can climb as high as 15%.^[7] Most women who develop eclampsia have had preeclampsia, a condition characterized by high blood pressure and protein in the urine. However, not all women with preeclampsia will progress to eclampsia, and in some cases, eclampsia can develop without prior signs of preeclampsia.^[2]

What Causes Eclampsia

The exact cause of eclampsia remains unclear to medical researchers, though several theories exist about what triggers this condition. Most experts believe eclampsia is related to problems with the placenta, the organ that connects the baby’s blood supply to the mother’s during pregnancy.^[1] When the placenta develops abnormally or experiences poor blood flow, it may set off a chain of events that eventually leads to eclampsia.

Several biological factors may contribute to the development of eclampsia. Genetic factors appear to play a role, as women with a family history of the condition are at higher risk. Inflammatory changes within the body, abnormalities in how blood clots, and inflammation in the brain may also be involved.^[1] Some researchers believe that hormone imbalances during pregnancy could contribute to the condition as well.

The development of uterine placental spiral arterioles—small blood vessels that supply the uterus and placenta—appears to be particularly important. In women who develop eclampsia, these blood vessels may not develop properly, leading to reduced blood flow to the placenta during the later stages of pregnancy.^[4] This reduced blood flow can cause the placenta to become oxygen-deprived, triggering a series of harmful effects throughout the mother’s body.

Another important factor involves damage to the endothelium, the inner lining of blood vessels. When this lining is damaged, it can cause blood vessels to constrict abnormally, leading to the high blood pressure seen in preeclampsia and eclampsia. The body’s production of certain substances—decreased levels of prostacyclin (which normally helps blood vessels relax) and increased levels of endothelin (which causes blood vessels to tighten)—may contribute to this dangerous constriction.^[4]

Who Is Most at Risk for Developing Eclampsia

The single biggest risk factor for eclampsia is having preeclampsia, the condition of high blood pressure and organ dysfunction during pregnancy. However, most women with preeclampsia do not go on to develop eclampsia.^[1] Understanding other risk factors can help women and their healthcare providers monitor pregnancies more closely and take preventive measures when appropriate.

First-time mothers face a higher risk of developing eclampsia compared to women who have been pregnant before. Women who are pregnant with twins, triplets, or other multiples also have an increased risk.^[1] Age plays a role as well—teenagers and women aged 35 or older are more likely to develop the condition than women in their twenties and early thirties.^[9]

Pre-existing medical conditions significantly increase the risk of eclampsia. Women with chronic high blood pressure before pregnancy, kidney disease, or diabetes face higher odds of developing this complication.^[1] Autoimmune disorders, such as lupus or antiphospholipid syndrome (a condition that causes abnormal blood clotting), also elevate risk.^[9]

Women who had preeclampsia or eclampsia in a previous pregnancy are more likely to experience it again. A family history of these conditions—having a mother or sister who had preeclampsia or eclampsia—also increases risk.^[1] Additionally, women who experienced certain pregnancy complications in the past, such as fetal growth restriction, stillbirth, or placental abruption (when the placenta detaches from the uterus prematurely), face higher risk in subsequent pregnancies.

Race and ethnicity appear to influence risk as well. Research shows that Black women and Hispanic women face higher rates of eclampsia compared to women of other racial and ethnic backgrounds.^[4] Women conceived through in vitro fertilization, those with obesity (defined as having a body mass index of 30 or greater), and those who went more than 10 years between pregnancies also have elevated risk.^[6]

Recognizing the Symptoms and Warning Signs

The most distinctive symptom of eclampsia is seizures. These seizures typically last between one and two minutes and are of the tonic-clonic type, meaning they involve both muscle stiffening and rhythmic jerking movements.^[7] During a seizure, a woman may experience facial twitching, rapid body-wide muscle contractions and relaxations, and foaming at the mouth. She typically becomes unconscious during or shortly after the seizure.^[1]

Following the seizure, women often go through a period of confusion or agitation as they regain consciousness. Many women experience rapid breathing, called hyperventilation, during seizure recovery, which occurs as the body tries to correct the respiratory and lactic acid buildup that happens during the seizure.^[4] Most women have no memory of the seizure itself.

Before seizures occur, many women experience warning signs that should prompt immediate medical attention. Severe, persistent headaches occur in about 66% of women who develop eclampsia.^[4] Visual disturbances affect approximately 27% of women and may include blurry vision, seeing spots or flashing lights, temporary vision loss, or seeing double. Pain in the upper abdomen, particularly on the right side just below the ribs, affects about 25% of women before they have a seizure.^[4]

Other warning signs include sudden, severe swelling of the face, hands, or feet; nausea and vomiting; difficulty breathing; and trouble urinating or urinating less frequently than normal.^[9] It’s important to note that some women may not experience obvious warning signs before their first seizure. High blood pressure readings are often present but may not cause symptoms that women notice on their own, which is why regular blood pressure monitoring during pregnancy is so critical.^[3]

Seizures caused by eclampsia can lead to several immediate complications. Some women bite their tongues during seizures, while others may hit their heads if they fall, potentially causing head trauma. Broken bones from falls are also possible.^[1] More serious complications can include difficulty breathing, aspiration pneumonia (which occurs when food or saliva is breathed into the lungs), blood clots, stroke, coma, heart failure, and in the most severe cases, death of the mother or baby.^[1]

Preventing Eclampsia and Protecting Pregnancy Health

The most effective way to prevent eclampsia is to attend all scheduled prenatal care appointments throughout pregnancy. Regular prenatal visits allow healthcare providers to monitor blood pressure and check for protein in the urine, the two main indicators of preeclampsia that typically appear before eclampsia develops.^[3] Early detection of preeclampsia makes it possible to manage the condition before it progresses to eclampsia.

For women at high risk of developing preeclampsia and eclampsia, healthcare providers may recommend taking low-dose aspirin daily. This preventive measure typically involves taking between 75 and 150 milligrams of aspirin per day, starting at the 12th week of pregnancy and continuing until the baby is born.^[6] Low-dose aspirin can help reduce the risk of preeclampsia developing in the first place, though it should only be taken under medical supervision and according to a provider’s specific recommendations.

In areas where dietary calcium intake is low, calcium supplementation during pregnancy may help reduce the risk of developing preeclampsia and eclampsia.^[7] Women who had high blood pressure before pregnancy should work with their healthcare providers to manage it with appropriate medications throughout their pregnancy. Keeping blood pressure well-controlled can help prevent the progression from chronic hypertension to preeclampsia and eclampsia.

Regular physical activity during pregnancy may offer some protective benefits against developing these conditions.^[7] Pregnant women should discuss with their healthcare providers what types and amounts of exercise are safe and appropriate for their individual situations. Avoiding tobacco, cannabis, and other substances is also critical, as these can affect both maternal health and the baby’s development.^[19]

For women with preeclampsia, especially those with severe features of the disease, healthcare providers may prescribe magnesium sulfate to prevent seizures from occurring. This medication is considered the first-line treatment for preventing eclampsia in women with severe preeclampsia.^[3] Many providers also use magnesium sulfate during labor for women with any form of preeclampsia, as eclampsia can develop even without prior signs of severe disease.

How the Body Changes in Eclampsia

Eclampsia causes widespread changes throughout the body, affecting multiple organ systems. The condition begins with changes in blood pressure and blood vessel function that can cascade into problems affecting the brain, kidneys, liver, blood clotting system, and placenta. Understanding these changes helps explain why eclampsia is such a serious condition requiring immediate medical attention.

In the brain, high blood pressure can cause blood vessels to spasm, or tighten abnormally. This vasospasm reduces blood flow to brain tissue and can lead to swelling in the brain.^[4] The combination of reduced blood flow and swelling creates conditions that can trigger seizures. In some cases, severe high blood pressure can cause bleeding in the brain, known as cerebral hemorrhage, which is one of the most dangerous complications of eclampsia.

The kidneys are particularly vulnerable to damage from the high blood pressure and blood vessel problems that occur in eclampsia. The filtering units of the kidneys may not work properly, leading to decreased urine output and the buildup of waste products in the blood. Protein begins to leak from the blood into the urine, which is why protein in the urine is a key sign of preeclampsia.^[9] In severe cases, acute kidney injury can occur, requiring intensive medical management.

The liver can also be affected by eclampsia. Blood vessel spasm in the liver can lead to areas of tissue damage and cause liver enzymes to become elevated in the blood. Some women develop pain in the upper right side of their abdomen as the liver swells. In rare but serious cases, the liver can rupture, causing life-threatening internal bleeding.^[1]

Changes in the blood clotting system are common in eclampsia. The number of platelets, blood cells responsible for clotting, often decreases significantly. This drop in platelet count, called thrombocytopenia, can increase the risk of bleeding.^[4] At the same time, the activation of the clotting system can lead to the formation of blood clots in blood vessels throughout the body, potentially blocking blood flow to vital organs.

In the lungs, fluid can accumulate, creating a condition called pulmonary edema. This fluid buildup makes breathing difficult and reduces the amount of oxygen getting into the blood.^[7] Difficulty breathing and shortness of breath are serious warning signs that require immediate emergency care.

The placenta suffers from reduced blood flow due to the abnormal blood vessel function throughout the body. This poor blood flow can restrict the baby’s growth during pregnancy, a condition called fetal growth restriction. In some cases, the placenta may separate from the wall of the uterus prematurely, a dangerous complication called placental abruption that can cause severe bleeding and threaten both mother and baby.^[1] The reduced oxygen supply to the baby can also lead to stillbirth in the most severe cases.

The heart must work harder to pump blood against the increased resistance caused by constricted blood vessels and high blood pressure. Over time, this extra work can lead to changes in the heart muscle and, in severe cases, heart failure.^[1] The cardiovascular stress from eclampsia can have long-lasting effects, with women who have had the condition facing increased risk of heart disease later in life.