Preeclampsia: Symptoms, Causes & Treatment Guide

What Is Preeclampsia?

Preeclampsia is a pregnancy-specific disorder characterized by new-onset high blood pressure (≥140/90 mmHg) and protein in the urine (proteinuria) or other organ dysfunction, typically occurring after 20 weeks of gestation. It is one of the leading causes of maternal and fetal morbidity and mortality worldwide, affecting 2-8% of all pregnancies.

Preeclampsia represents a complex, multisystem disorder that originates in the placenta and affects multiple organ systems in the mother. The condition is thought to begin early in pregnancy with abnormal development of the blood vessels that supply the placenta, but clinical signs typically don't appear until the second half of pregnancy. Understanding this condition is crucial for pregnant women and their families, as early recognition and proper management can prevent serious complications.

The name "preeclampsia" comes from the Greek word "eklampsis," meaning "lightning" or "sudden flash," referring to the seizures (eclampsia) that can occur as a severe complication. Historically, the condition was called "toxemia of pregnancy" because doctors believed it was caused by toxins in the blood, though we now know the underlying causes are much more complex and related to placental function and the maternal immune response.

Preeclampsia exists on a spectrum from mild to severe, and its progression can be unpredictable. Some women experience gradual worsening over weeks, while others can deteriorate rapidly within hours. This unpredictability underscores the importance of close monitoring and the need for immediate medical attention when warning signs appear. The condition can affect virtually every organ system in the body, including the cardiovascular system, kidneys, liver, brain, and blood clotting mechanisms.

Types of Hypertensive Disorders in Pregnancy

Understanding preeclampsia requires distinguishing it from other blood pressure conditions during pregnancy. The International Society for the Study of Hypertension in Pregnancy (ISSHP) classifies hypertensive disorders of pregnancy into four main categories, each with different implications for maternal and fetal health.

Chronic hypertension refers to high blood pressure that was present before pregnancy or develops before 20 weeks of gestation. Women with chronic hypertension have an increased risk of developing superimposed preeclampsia, where the preeclampsia develops on top of existing hypertension, often with more severe manifestations.

Gestational hypertension is elevated blood pressure that first appears after 20 weeks without proteinuria or other signs of organ dysfunction. About 25% of women with gestational hypertension will progress to preeclampsia, so careful monitoring is essential. If the condition resolves after delivery, the diagnosis is confirmed as gestational hypertension.

Preeclampsia-eclampsia represents the spectrum from preeclampsia to its most severe complication—seizures (eclampsia). Preeclampsia can occur with or without severe features, and the distinction is important for determining the urgency of delivery and the intensity of monitoring required.

How Common Is Preeclampsia?

Preeclampsia affects approximately 2-8% of pregnancies globally, though rates vary significantly by region, with higher prevalence in developing countries where access to prenatal care may be limited. In high-income countries with good prenatal care, severe complications have become less common, though the condition remains a leading cause of maternal mortality worldwide, accounting for 10-15% of maternal deaths globally.

The incidence of preeclampsia has been increasing in many developed countries, likely due to rising rates of obesity, diabetes, and advanced maternal age—all risk factors for the condition. Additionally, improvements in diagnostic criteria and more comprehensive prenatal screening have led to earlier and more frequent detection.

What Are the Symptoms of Preeclampsia?

The main symptoms of preeclampsia include high blood pressure (140/90 mmHg or higher), protein in the urine, severe headaches that don't respond to medication, vision changes (blurred vision, seeing spots, or light sensitivity), upper right abdominal pain under the ribs, sudden swelling of the face and hands, rapid weight gain, nausea and vomiting, and decreased urination. Many women have no symptoms initially, making regular prenatal checkups essential.

One of the challenging aspects of preeclampsia is that it can develop without obvious symptoms, which is why routine prenatal care with regular blood pressure monitoring and urine testing is so important. Many women feel completely well even when their blood pressure is significantly elevated. This "silent" nature of early preeclampsia underscores why it's often called the "silent killer" of pregnancy.

When symptoms do develop, they can range from subtle to dramatic. The progression from mild to severe preeclampsia can occur gradually over days to weeks, or it can happen suddenly within hours. Understanding the warning signs can help women seek timely medical care and potentially prevent serious complications.

High Blood Pressure

Elevated blood pressure is the defining feature of preeclampsia. A diagnosis requires systolic blood pressure of 140 mmHg or higher, or diastolic blood pressure of 90 mmHg or higher, on two measurements taken at least 4 hours apart. Severely elevated blood pressure—systolic of 160 mmHg or higher or diastolic of 110 mmHg or higher—indicates severe preeclampsia and requires urgent treatment.

Many women don't feel any different when their blood pressure is elevated, which is why home blood pressure monitoring is sometimes recommended for high-risk women. Symptoms that may occur with very high blood pressure include headaches, dizziness, and visual disturbances, though these can also occur without extremely elevated readings.

Severe Headaches

Headaches associated with preeclampsia are typically severe, persistent, and don't respond to over-the-counter pain medications like acetaminophen. They may be described as the "worst headache of my life" and often feel different from typical pregnancy headaches or migraines. These headaches can indicate cerebral swelling or increased pressure in the brain and should prompt immediate medical evaluation.

The location of the headache is often frontal (affecting the forehead) or may be felt throughout the head. It may be accompanied by visual disturbances, confusion, or difficulty concentrating. Any new-onset severe headache in the second half of pregnancy should be taken seriously and evaluated promptly.

Vision Changes

Visual disturbances in preeclampsia can include blurred vision, seeing flashing lights or spots (similar to an aura before a migraine), temporary vision loss, light sensitivity (photophobia), and difficulty focusing. These symptoms may indicate swelling of the brain or reduced blood flow to the visual centers and can precede eclamptic seizures.

Any sudden changes in vision during pregnancy, especially after 20 weeks, warrant immediate medical attention. These symptoms should never be dismissed as "normal pregnancy changes" as they can indicate serious complications requiring urgent treatment.

Upper Abdominal Pain

Pain in the upper right side of the abdomen, particularly under the ribs, can indicate liver involvement in preeclampsia. This pain is caused by stretching of the liver capsule due to swelling and can be a sign of HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets), a severe complication. The pain may be mistaken for heartburn, gallbladder disease, or stomach upset.

The liver involvement in severe preeclampsia can lead to serious complications including liver rupture, though this is rare with prompt treatment. Upper abdominal pain that is persistent, severe, or accompanied by other preeclampsia symptoms requires immediate evaluation.

Swelling and Weight Gain

While some swelling is normal during pregnancy, sudden or severe swelling of the face, hands, and feet, particularly if it doesn't improve with rest, can be a sign of preeclampsia. This type of swelling is caused by fluid leaking from blood vessels into tissues due to the vascular changes associated with the condition.

Rapid weight gain—more than 2 kilograms (about 5 pounds) in a week—can indicate fluid retention associated with preeclampsia and should be reported to your healthcare provider. However, it's important to note that many women with preeclampsia don't have significant swelling, so the absence of edema doesn't rule out the condition.

What Causes Preeclampsia?

The exact cause of preeclampsia is not fully understood, but it involves abnormal placental development early in pregnancy, leading to poor blood flow to the placenta and release of substances that damage the mother's blood vessel lining. Contributing factors include immune system dysfunction, genetic predisposition, existing vascular disease, and metabolic factors. The condition always originates in the placenta, which is why delivery is the only cure.

Preeclampsia is fundamentally a placental disease. Current scientific understanding suggests that the condition begins very early in pregnancy—during the first trimester—when the placenta is forming. In a healthy pregnancy, specialized cells from the placenta (trophoblasts) invade the walls of the uterine arteries, remodeling them to create large, low-resistance vessels that can deliver the massive blood flow needed by the growing baby.

In pregnancies that will develop preeclampsia, this remodeling process is incomplete or defective. The uterine arteries remain narrow and constricted, limiting blood flow to the placenta. This creates a state of placental ischemia (insufficient blood supply) and oxidative stress, which causes the placenta to release various substances into the maternal circulation.

These placental-derived factors cause widespread damage to the endothelium—the cells lining all the mother's blood vessels. This endothelial dysfunction leads to vasoconstriction (narrowing of blood vessels), increased vascular permeability (leaky blood vessels), and activation of the clotting system. The result is the clinical manifestations of preeclampsia: high blood pressure, protein in the urine from kidney damage, liver dysfunction, and potentially more severe complications.

Immune System Factors

The immune system plays a crucial role in establishing a successful pregnancy. The fetus carries genetic material from both parents, making it "foreign" from the mother's immune perspective. Normally, the maternal immune system develops tolerance to the fetal tissues, but in preeclampsia, this tolerance may be impaired, leading to an inflammatory response that contributes to placental dysfunction.

Research has shown that the risk of preeclampsia is higher in first pregnancies, after a change in partner, or after long intervals between pregnancies—all situations where the maternal immune system may be less "familiar" with the paternal antigens. This has led to theories that inadequate maternal immune adaptation to the pregnancy may be involved in the development of preeclampsia.

Genetic Factors

There is a significant genetic component to preeclampsia risk. Women whose mothers or sisters had preeclampsia are at 2-5 times higher risk of developing the condition themselves. Similarly, men who fathered a preeclamptic pregnancy are more likely to father another preeclamptic pregnancy with a different partner, suggesting paternal genetic contributions as well.

Multiple genes have been identified that may influence preeclampsia risk, including genes involved in blood pressure regulation, immune function, and placental development. However, no single gene accounts for the majority of cases, and the genetic basis is likely polygenic (involving many genes) and influenced by environmental factors.

Who Is at Risk for Preeclampsia?

Major risk factors for preeclampsia include first pregnancy (nulliparity), previous preeclampsia, chronic hypertension, diabetes (type 1, type 2, or gestational), kidney disease, obesity (BMI over 30), multiple pregnancy (twins or more), advanced maternal age (over 35-40), family history of preeclampsia, and autoimmune conditions such as lupus or antiphospholipid syndrome. Having multiple risk factors increases the overall risk significantly.

Understanding risk factors for preeclampsia is crucial because it allows for early identification of women who may benefit from preventive measures, closer monitoring, and earlier intervention when problems develop. Risk factors can be broadly categorized into those related to the current pregnancy, the mother's medical history, and the pregnancy history.

First Pregnancy

First-time mothers (nulliparous women) have a 2-3 times higher risk of preeclampsia compared to women who have had previous pregnancies. This is thought to be related to the maternal immune system's first exposure to fetal/paternal antigens. Interestingly, the protective effect of a previous pregnancy may be lost if there is a change in partner, supporting the immune adaptation theory.

Previous Preeclampsia

A history of preeclampsia in a previous pregnancy is one of the strongest risk factors for recurrence, increasing the risk approximately 7-fold. The recurrence risk is higher (25-65%) if the previous episode was severe, occurred early in pregnancy (before 34 weeks), or resulted in HELLP syndrome. Women with a history of preeclampsia should discuss prevention strategies with their healthcare provider early in subsequent pregnancies.

Chronic Medical Conditions

Several chronic conditions significantly increase preeclampsia risk. Chronic hypertension raises the risk 5-fold and predisposes to the more severe "superimposed preeclampsia." Diabetes—whether type 1, type 2, or gestational—increases risk 2-4 fold due to vascular damage and metabolic dysfunction. Kidney disease impairs the body's ability to regulate blood pressure and fluid balance. Autoimmune conditions, particularly lupus and antiphospholipid syndrome, carry substantially elevated risks due to underlying vascular inflammation and clotting abnormalities.

How Is Preeclampsia Diagnosed?

Preeclampsia is diagnosed when a pregnant woman develops high blood pressure (systolic ≥140 mmHg or diastolic ≥90 mmHg) after 20 weeks of gestation, combined with proteinuria (≥300 mg protein in 24-hour urine) or signs of organ dysfunction such as elevated liver enzymes, low platelet count, kidney impairment, pulmonary edema, or neurological symptoms. Diagnosis requires blood pressure measurements on two occasions at least 4 hours apart.

The diagnosis of preeclampsia relies on clinical assessment and laboratory testing. Regular prenatal care is essential for early detection, as many women have no symptoms when preeclampsia first develops. The diagnostic process involves measuring blood pressure, testing urine for protein, and performing blood tests to assess organ function.

Blood Pressure Measurement

Accurate blood pressure measurement is fundamental to diagnosing preeclampsia. The diagnosis requires elevated blood pressure on at least two occasions, measured at least 4 hours apart (or within a shorter interval if blood pressure is severely elevated). Proper technique is important: the woman should be seated comfortably, with feet flat on the floor, back supported, and arm at heart level. An appropriately sized cuff should be used—a cuff that is too small will give falsely elevated readings.

Urine Testing

Proteinuria (protein in the urine) is a classic feature of preeclampsia, though current guidelines recognize that preeclampsia can be diagnosed without proteinuria if other features of organ dysfunction are present. The gold standard for measuring proteinuria is a 24-hour urine collection, with ≥300 mg of protein indicating significant proteinuria. The protein-to-creatinine ratio from a spot urine sample is a faster alternative that correlates well with 24-hour values.

Blood Tests

Several blood tests help assess the severity of preeclampsia and detect organ involvement. These include complete blood count (looking for low platelets), liver function tests (AST and ALT enzymes), kidney function tests (creatinine and uric acid), and clotting studies. In severe preeclampsia or HELLP syndrome, hemolysis markers (LDH, bilirubin, haptoglobin) may also be abnormal.

Fetal Assessment

Because preeclampsia affects the placenta and can compromise fetal well-being, assessment of the baby is an essential part of the diagnostic and monitoring process. This typically includes fetal heart rate monitoring (non-stress test), ultrasound to assess fetal growth, amniotic fluid volume, and Doppler studies of umbilical artery blood flow, which can detect signs of placental insufficiency.

How Is Preeclampsia Treated?

The only cure for preeclampsia is delivery of the baby and placenta. Treatment depends on severity and gestational age: mild preeclampsia may be managed with close monitoring, blood pressure medications, and expectant management until the baby is mature enough for delivery. Severe preeclampsia requires hospitalization, magnesium sulfate to prevent seizures, antihypertensive medications to control blood pressure, corticosteroids for fetal lung maturation if preterm, and often prompt delivery.

The management of preeclampsia involves balancing the risks of continuing the pregnancy against the risks of preterm delivery for the baby. In early preeclampsia (before 34 weeks), expectant management may allow additional time for fetal maturation, but this must be weighed against the risk of disease progression in the mother. In later pregnancy (after 37 weeks), delivery is generally recommended as the baby is mature and the risks of continuing outweigh the benefits.

Magnesium Sulfate

Magnesium sulfate is the most important medication for preventing eclamptic seizures in women with severe preeclampsia. It is given intravenously and is remarkably effective—reducing the risk of eclampsia by about 50%. The medication is typically started when severe features are present and continued for 24-48 hours after delivery. Side effects can include flushing, warmth, and muscle weakness, and toxic levels can cause respiratory depression, requiring careful monitoring.

Blood Pressure Medications

Antihypertensive medications are used to control severely elevated blood pressure and prevent complications such as stroke. Commonly used medications include labetalol (a beta-blocker), nifedipine (a calcium channel blocker), and hydralazine. The goal is not to normalize blood pressure completely but to bring it to a safe range (usually 140-150/90-100 mmHg) to prevent hypertensive complications while maintaining adequate blood flow to the placenta.

Corticosteroids for Fetal Lung Maturation

If delivery before 34 weeks is anticipated, corticosteroids (betamethasone or dexamethasone) are given to accelerate fetal lung development and reduce the risk of respiratory distress syndrome in the newborn. These medications take about 48 hours to achieve maximum effect, so when possible, delivery is delayed to allow the steroids to work. Corticosteroids have been one of the most important interventions for improving outcomes in preterm babies.

Timing of Delivery

The decision about when to deliver involves careful consideration of gestational age, disease severity, maternal condition, and fetal status. Current guidelines generally recommend delivery at 37 weeks for preeclampsia without severe features, and prompt delivery for severe preeclampsia after 34 weeks or earlier if the mother or baby's condition is deteriorating. The mode of delivery (vaginal or cesarean) depends on the urgency of delivery, cervical status, and other obstetric factors.

Can Preeclampsia Be Prevented?

While preeclampsia cannot always be prevented, low-dose aspirin (75-150 mg daily) started before 16 weeks of pregnancy reduces the risk by approximately 17% in high-risk women. Other preventive strategies include regular prenatal care for early detection, maintaining a healthy weight before pregnancy, adequate calcium supplementation in populations with low calcium intake, and managing chronic conditions like hypertension and diabetes before conception.

Prevention of preeclampsia has been an active area of research for decades. While no intervention can completely eliminate the risk, several strategies have been shown to reduce the likelihood of developing the condition, particularly in high-risk women. The most well-established preventive measure is low-dose aspirin.

Low-Dose Aspirin

Low-dose aspirin (75-150 mg daily, typically 81 mg in the United States or 100 mg in other countries) has been proven to reduce the risk of preeclampsia by about 17% when started before 16 weeks of gestation in high-risk women. The benefit is greatest when aspirin is started early (before 16 weeks) and taken consistently until delivery. Aspirin is thought to work by improving placental blood flow and reducing inflammation.

Current guidelines recommend low-dose aspirin for women with any high-risk factor (such as previous preeclampsia, chronic hypertension, diabetes, kidney disease, or autoimmune disease) or multiple moderate-risk factors (such as first pregnancy, maternal age over 35, obesity, or family history of preeclampsia). The medication is safe in pregnancy and does not increase the risk of bleeding complications at low doses.

Calcium Supplementation

In populations with low dietary calcium intake (less than 600 mg per day), calcium supplementation has been shown to reduce the risk of preeclampsia and gestational hypertension. The World Health Organization recommends 1.5-2 grams of calcium daily for pregnant women with low calcium intake. However, in populations with adequate dietary calcium, supplementation does not appear to provide additional benefit.

Lifestyle Factors

While lifestyle modifications alone cannot prevent preeclampsia, maintaining a healthy weight before pregnancy reduces risk. Obesity is associated with a 2-4 fold increased risk of preeclampsia, and weight loss before conception can help. During pregnancy, a balanced diet rich in fruits, vegetables, and whole grains, along with appropriate physical activity, supports overall health, though specific dietary interventions have not been proven to prevent preeclampsia.

What Are the Complications of Preeclampsia?

Serious complications of preeclampsia include eclampsia (seizures), HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), stroke, pulmonary edema, acute kidney failure, placental abruption, liver rupture, and disseminated intravascular coagulation. For the baby, complications include intrauterine growth restriction, preterm birth, low birth weight, and stillbirth. Most complications are preventable with early detection and appropriate management.

While most women with preeclampsia have successful pregnancies with proper management, the condition can lead to serious complications if it progresses or is not adequately treated. Understanding potential complications emphasizes the importance of regular prenatal care, recognition of warning signs, and timely medical intervention.

Eclampsia

Eclampsia refers to the occurrence of generalized tonic-clonic seizures in a woman with preeclampsia. It is one of the most feared complications and can occur before, during, or after delivery (most commonly within 48 hours of delivery). Eclamptic seizures can cause maternal injury, aspiration, hypoxia, and rarely, death. Magnesium sulfate is highly effective at preventing eclampsia in women with severe preeclampsia, reducing the risk by about 50%.

HELLP Syndrome

HELLP syndrome is a severe form of preeclampsia characterized by Hemolysis (destruction of red blood cells), Elevated Liver enzymes (indicating liver damage), and Low Platelets (increasing bleeding risk). It occurs in about 10-20% of severe preeclampsia cases and can develop rapidly, sometimes before high blood pressure is significantly elevated. HELLP syndrome carries risks of liver rupture, stroke, kidney failure, and maternal death, requiring urgent delivery and intensive management.

Placental Abruption

Placental abruption, where the placenta separates from the uterine wall before delivery, occurs in about 1-3% of preeclamptic pregnancies compared to 0.5-1% in the general population. Abruption can cause severe bleeding, fetal distress, and may necessitate emergency cesarean delivery. It is a life-threatening condition for both mother and baby.

Long-Term Health Consequences

Preeclampsia is associated with increased long-term cardiovascular risk for both mother and child. Women who have had preeclampsia have approximately double the risk of heart disease, stroke, and chronic hypertension later in life. These women should maintain regular cardiovascular health monitoring, manage modifiable risk factors, and discuss their pregnancy history with their healthcare providers. The increased risk appears to persist for decades after the affected pregnancy.

What Happens After Delivery?

Preeclampsia typically resolves within days to weeks after delivery, as the placenta is removed. However, blood pressure may initially rise in the first few days postpartum before gradually normalizing. Close monitoring continues for 72 hours to 2 weeks after delivery. Delayed postpartum preeclampsia can occur up to 6 weeks after delivery. Long-term follow-up is recommended due to increased cardiovascular risk.

Delivery of the baby and placenta is the definitive treatment for preeclampsia, but the condition doesn't resolve immediately. Blood pressure often peaks in the first 3-6 days after delivery before beginning to improve. Most women see normalization of their blood pressure within 12 weeks of delivery, though some may require continued antihypertensive medication for weeks to months.

Postpartum monitoring is essential because serious complications, including eclampsia and stroke, can occur after delivery. Women should be aware of warning signs and seek immediate medical attention for severe headaches, vision changes, upper abdominal pain, difficulty breathing, or significantly elevated blood pressure. Delayed postpartum preeclampsia, occurring more than 48 hours after delivery, accounts for about 25% of postpartum cases and can occur up to 6 weeks after delivery.

Breastfeeding Considerations

Breastfeeding is encouraged for women who had preeclampsia, as it provides important health benefits for both mother and baby. Most blood pressure medications used postpartum are compatible with breastfeeding, though some may be preferred over others. Labetalol, nifedipine, and enalapril are generally considered safe during breastfeeding. Your healthcare provider can help select appropriate medications if needed.

Future Pregnancy Planning

Women who have had preeclampsia should discuss future pregnancies with their healthcare provider. The recurrence risk is approximately 15-20% for subsequent pregnancies, higher if the preeclampsia was severe or occurred early. Starting low-dose aspirin before 16 weeks in the next pregnancy can reduce the recurrence risk. Preconception optimization of weight, blood pressure, and any chronic conditions can also help reduce risk.