Preeclampsia - Pathophysiology

SECTION 1

Historical Context & Motivation

The clinical recognition of preeclampsia stretches back millennia, though ancient physicians lacked the tools to distinguish it from other convulsive disorders of pregnancy. Hippocratic writings from the fourth century BCE described seizures in gravid women as a grave omen, yet the relationship between proteinuria, hypertension, and eclamptic fits would not be elucidated for over two thousand years. Throughout the nineteenth century, the advent of urinalysis and sphygmomanometry transformed obstetric practice, allowing clinicians to identify the prodromal signs of what was once an unpredictable catastrophe. Today, preeclampsia complicates approximately 2–8% of pregnancies globally, accounting for an estimated 70,000 maternal deaths and 500,000 fetal or neonatal deaths each year, making its pathophysiology one of the most intensively studied problems in reproductive medicine.

1840s • Proteinuria Linked to Eclampsia

John Lever demonstrated that women who developed convulsions during pregnancy consistently exhibited albumin in their urine, establishing proteinuria as a key diagnostic marker preceding eclamptic seizures.

1897 • Blood Pressure Measurement in Pregnancy

Riva-Rocci's mercury sphygmomanometer enabled routine blood pressure monitoring in pregnant women, and clinicians soon correlated hypertension with the proteinuric syndrome that preceded eclampsia.

1972 • Two-Stage Disease Model Proposed

C.W.G. Redman and colleagues articulated the concept that preeclampsia originates with defective placentation (Stage 1) followed by a maternal systemic inflammatory response (Stage 2), establishing the foundational two-stage model still referenced today.

2003 • Angiogenic Imbalance Identified

S. Ananth Karumanchi's laboratory identified elevated soluble fms-like tyrosine kinase-1 (sFlt-1) and reduced placental growth factor (PlGF) in preeclamptic sera, providing a molecular basis for the endothelial dysfunction observed clinically.

2013 • ACOG Redefines Diagnostic Criteria

The American College of Obstetricians and Gynecologists updated its guidelines, recognizing that preeclampsia can present with severe features—thrombocytopenia, renal insufficiency, hepatic dysfunction—even in the absence of proteinuria.

Despite these advances, the precise etiology of preeclampsia remains incompletely understood, and definitive treatment still requires delivery of the placenta. The central question driving current research is: how does abnormal trophoblast invasion of the uterine spiral arteries set off a cascade of anti-angiogenic signaling, endothelial injury, and multi-organ dysfunction that characterizes the maternal syndrome? This lesson explores that question systematically.

SECTION 2

Core Principles & Definitions

Understanding preeclampsia requires a firm grasp of several interlocking pathophysiological concepts. The disease is not merely a form of high blood pressure; it is a systemic endothelial syndrome originating from placental dysfunction that manifests across multiple organ systems. Before dissecting its molecular mechanisms, clinicians must internalize the foundational definitions and principles that frame the disorder.

Diagnostic Threshold

New-onset blood pressure ≥ 140/90 mmHg on two occasions at least 4 hours apart, arising after 20 weeks of gestation in a previously normotensive woman, accompanied by proteinuria (≥ 300 mg/24 h) or evidence of end-organ damage.

Two-Stage Pathogenesis

Stage 1 involves defective trophoblast invasion and incomplete spiral artery remodeling during weeks 8–18 of gestation, creating placental ischemia. Stage 2 is the resulting maternal syndrome of systemic endothelial dysfunction.

Angiogenic Imbalance

The ischemic placenta releases excess anti-angiogenic factors (sFlt-1, soluble endoglin) that sequester pro-angiogenic molecules (VEGF, PlGF), depriving maternal endothelial cells of essential survival signals and triggering widespread vascular dysfunction.

Severity Spectrum

Preeclampsia exists on a continuum from mild disease (blood pressure 140–159/90–109 mmHg, modest proteinuria) to severe disease (blood pressure ≥ 160/110 mmHg, thrombocytopenia, elevated liver enzymes, renal failure) and can progress to eclampsia (seizures) or HELLP syndrome.

Definitive Treatment

Delivery of the placenta remains the only cure. Management before delivery centers on blood pressure control, seizure prophylaxis with magnesium sulfate, and careful fetal surveillance to balance maternal safety against neonatal prematurity.

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KEY TAKEAWAY

Think of the placenta in preeclampsia like a faulty thermostat in a building's HVAC system. In normal pregnancy, the trophoblasts remodel the spiral arteries (the thermostat correctly senses and regulates temperature), ensuring steady blood flow. In preeclampsia, the thermostat is miscalibrated: it detects an energy deficit (ischemia), so it cranks up the system (releases sFlt-1 and inflammatory mediators). Unfortunately, this 'fix' overheats every room in the building—the kidneys, liver, brain, and vasculature—causing damage far from the source of the original malfunction.

SECTION 3

Visual Explanation — The Two-Stage Model

The diagram below illustrates the two-stage pathogenesis of preeclampsia. Stage 1 (left) depicts the defective trophoblast invasion and inadequate spiral artery remodeling that produce placental ischemia. Stage 2 (right) shows how anti-angiogenic factors released from the ischemic placenta disrupt the maternal endothelium, culminating in the clinical syndrome of hypertension, proteinuria, and end-organ damage.

The two-stage model of preeclampsia. On the left (Stage 1), defective trophoblast invasion leads to unremodeled spiral arteries with narrow lumens and high resistance, producing placental ischemia. Anti-angiogenic factors (sFlt-1, soluble endoglin) enter the maternal circulation, triggering Stage 2 (right): systemic endothelial dysfunction affecting the kidneys, liver, brain, and vasculature. Severe progression may result in eclampsia or HELLP syndrome.

As illustrated in the diagram, the transition from Stage 1 to Stage 2 depends on the volume and ratio of anti-angiogenic factors entering the maternal bloodstream. In normal pregnancy, the spiral arteries are transformed into wide, low-resistance conduits by invasive extravillous trophoblasts that replace endothelial and smooth-muscle layers. When this remodeling fails, the resulting uteroplacental mismatch between fetal oxygen demand and maternal blood supply drives hypoxic signaling cascades that culminate in the release of sFlt-1 and soluble endoglin. These molecules do not act locally; they enter the systemic circulation and strip the endothelium of its protective vasodilators, most notably nitric oxide and prostacyclin, precipitating the clinical features of the disease.

SECTION 4

Molecular Mechanisms & Pathophysiology

At the molecular level, preeclampsia can be understood as a collision between the placenta's adaptive response to ischemia and the maternal endothelium's capacity to withstand that response. Several interconnected signaling axes underlie this process, and their quantitative relationships help explain why some women develop mild disease while others progress to life-threatening complications.

Angiogenic Factor Imbalance

In normal pregnancy, vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) bind their receptors on endothelial cells (primarily VEGFR-2 and Flt-1), activating downstream PI3K/Akt signaling that promotes endothelial nitric oxide synthase (eNOS) activity, vascular permeability regulation, and endothelial survival. In preeclampsia, the hypoxic placenta dramatically upregulates the production of sFlt-1, a truncated splice variant of the Flt-1 receptor that lacks the transmembrane domain. Circulating sFlt-1 acts as a molecular sponge, binding free VEGF and PlGF in the plasma before they can reach the endothelium. The result is a state of functional angiogenic factor deprivation despite adequate total production of these ligands.

ANTI-ANGIOGENIC RATIO

sFlt-1 / PlGF ratio ≥ 38 → high probability of preeclampsia within 4 weeks

An sFlt-1/PlGF ratio below 38 has a negative predictive value exceeding 99% for ruling out preeclampsia within one week (PROGNOSIS study). Values above 85 in early-onset disease or above 110 in late-onset disease indicate established preeclampsia with high positive predictive value.

Endothelial Nitric Oxide & Vasomotor Tone

VEGF normally stimulates eNOS via Akt-mediated phosphorylation, producing nitric oxide (NO), a potent vasodilator that maintains low systemic vascular resistance (SVR) during pregnancy. When sFlt-1 sequesters VEGF, NO bioavailability plummets. Simultaneously, the stressed endothelium increases production of the vasoconstrictor endothelin-1 (ET-1) and thromboxane A₂ while reducing prostacyclin synthesis. This shift in the vasodilator-vasoconstrictor balance raises SVR and produces the characteristic vasospastic hypertension of preeclampsia.

MEAN ARTERIAL PRESSURE

MAP = CO × SVR

Where MAP = mean arterial pressure, CO = cardiac output, and SVR = systemic vascular resistance. In preeclampsia, SVR rises markedly due to endothelial-mediated vasospasm, and cardiac output may be normal or reduced, leading to elevated MAP.

Renal Pathology — Glomerular Endotheliosis

The kidney is exquisitely sensitive to VEGF deprivation because podocytes constitutively produce VEGF to sustain the adjacent glomerular endothelium. When circulating sFlt-1 neutralizes this paracrine VEGF, the glomerular endothelial cells swell—a lesion pathognomonic of preeclampsia known as glomerular endotheliosis. The swollen endothelium narrows or obliterates capillary lumens, impairing the glomerular filtration barrier and permitting albumin to escape into the urine. This process explains both the proteinuria and the decline in glomerular filtration rate (GFR) observed clinically. Of note, hyperuricemia in preeclampsia arises from reduced uric acid clearance secondary to diminished GFR and increased proximal tubular reabsorption.

Inflammatory & Coagulation Cascades

Endothelial activation in preeclampsia triggers a systemic inflammatory response characterized by elevated circulating levels of TNF-α, IL-6, and C-reactive protein. Injured endothelium exposes subendothelial collagen and releases tissue factor, activating the extrinsic coagulation cascade and promoting platelet aggregation. The consumptive coagulopathy that follows—thrombocytopenia, elevated fibrin degradation products, and microangiopathic hemolysis—constitutes the core features of HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets), a severe variant of preeclampsia.

SECTION 5

Classification & Diagnostic Criteria

Preeclampsia is classified along several axes—timing of onset, severity of features, and presence of superimposed conditions—each of which carries distinct pathophysiological implications and management strategies. The following visual and table summarize the current ACOG classification framework and its clinical correlates.

Classification spectrum of hypertensive disorders of pregnancy, ranging from gestational hypertension (lower risk) through preeclampsia without severe features and preeclampsia with severe features to eclampsia/HELLP syndrome. Lower panels contrast early-onset versus late-onset disease and enumerate major risk factors.

Feature	PE without Severe Features	PE with Severe Features
Blood Pressure	≥ 140/90 but < 160/110 mmHg	≥ 160/110 mmHg on two occasions 4 h apart (or once if treated)
Proteinuria	≥ 300 mg/24 h or protein/creatinine ratio ≥ 0.3	May be absent; diagnosis can rest on other severe criteria
Platelets	≥ 100,000/µL	< 100,000/µL (thrombocytopenia)
Liver Enzymes	Normal	AST or ALT ≥ 2× upper limit of normal
Renal Function	Creatinine ≤ 1.1 mg/dL	Creatinine > 1.1 mg/dL or doubling in absence of other renal disease
CNS Symptoms	Absent	Persistent headache, visual disturbances, altered mental status
Pulmonary	No edema	Pulmonary edema
Delivery Timing	37+0 weeks	34+0 weeks, or earlier if unstable

Comparison of preeclampsia without and with severe features based on ACOG 2020 guidelines

SECTION 6

Worked Example — Clinical Case Analysis

The following case illustrates how clinicians integrate history, examination findings, and laboratory data to diagnose preeclampsia, classify its severity, and formulate a management plan. Work through each step as though you were the admitting provider.

Case: 28-Year-Old Nulliparous Woman at 32 Weeks' Gestation

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Step 1 — Gather Clinical Data

A 28-year-old G1P0 presents at 32 weeks of gestation with a two-day history of frontal headache and bilateral lower-extremity edema. Her prenatal course was unremarkable until today. Vital signs: BP 162/108 mmHg (confirmed on repeat 4 hours later at 158/106 mmHg), HR 88 bpm, RR 18. Urine dipstick: 3+ protein.
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Step 2 — Order Confirmatory Studies

A 24-hour urine collection yields 1,200 mg of protein. Serum labs reveal: platelet count 82,000/µL (low), AST 148 U/L (elevated, normal < 40), ALT 162 U/L (elevated), creatinine 1.3 mg/dL (elevated from baseline 0.6), LDH 720 IU/L (elevated), and peripheral smear shows schistocytes. Uric acid is 7.8 mg/dL.
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Step 3 — Classify the Disorder

The patient meets criteria for preeclampsia with severe features based on multiple criteria: BP ≥ 160/110, platelet count < 100,000/µL, serum creatinine > 1.1 mg/dL, and transaminases > 2× the upper limit of normal. Furthermore, the triad of hemolysis (schistocytes, elevated LDH), elevated liver enzymes, and low platelets qualifies her for a concurrent diagnosis of HELLP syndrome.

Diagnosis: Preeclampsia with severe features / HELLP syndrome at 32 weeks
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Step 4 — Initiate Management

Immediate priorities include: (1) Seizure prophylaxis with a magnesium sulfate loading dose of 4–6 g IV over 20 minutes followed by a maintenance infusion of 1–2 g/h; (2) Antihypertensive therapy with IV labetalol 20 mg or IV hydralazine 5–10 mg to bring systolic BP below 160 and diastolic below 110; (3) Antenatal corticosteroids (betamethasone 12 mg IM × 2 doses, 24 hours apart) to accelerate fetal lung maturation, as the fetus is 32 weeks.
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Step 5 — Determine Delivery Timing

Because HELLP syndrome is an indication for delivery regardless of gestational age, this patient should be delivered within 24–48 hours, ideally after completing the corticosteroid course. If the maternal condition deteriorates (rising transaminases, falling platelets, DIC, or abruption), emergent delivery is warranted immediately. The route of delivery depends on obstetric factors: if the cervix is favorable, induction of labor may be attempted; otherwise, cesarean delivery is performed.

Plan: Delivery within 24–48 hours after corticosteroid course; MgSO₄ continued through delivery and for 24–48 h postpartum

SECTION 7

Management Strategies — Strengths & Limitations

The management of preeclampsia involves a careful balancing act between maternal safety and fetal maturity. No pharmacologic therapy reverses the underlying placental pathology; all interventions either mitigate symptoms, prevent complications, or buy time for the fetus to mature. Understanding the strengths and limitations of each major approach is essential for clinical decision-making.

Intervention	Strengths	Limitations
Magnesium Sulfate	Reduces eclampsia risk by ~58% (Magpie Trial); neuroprotective for preterm fetus; well-established safety profile	Does not lower blood pressure or reverse disease progression; risk of toxicity (respiratory depression, loss of deep tendon reflexes) requires monitoring serum Mg²⁺ levels
IV Antihypertensives (Labetalol, Hydralazine, Nifedipine)	Rapidly control severe hypertension (target < 160/110); reduce risk of maternal stroke and hemorrhage	Symptomatic relief only; do not address underlying endothelial dysfunction; excessive BP reduction can compromise uteroplacental perfusion
Antenatal Corticosteroids	Accelerate fetal lung maturity; reduce neonatal RDS, IVH, and mortality; transient improvement in maternal platelet count	Require 24–48 hours for maximum effect; do not alter maternal disease trajectory; may transiently worsen maternal glucose control
Expectant Management (Remote from Term)	Each additional day in utero below 34 weeks significantly reduces neonatal morbidity; allows time for corticosteroid benefit	Risk of maternal deterioration (abruption, DIC, stroke, organ failure); requires ICU-level surveillance; contraindicated in unstable HELLP
Delivery (Definitive)	Removes the source of anti-angiogenic factors; syndrome typically resolves within 48 hours postpartum	If preterm, carries significant neonatal risks; rare postpartum preeclampsia can still occur; long-term maternal cardiovascular risk persists
Low-Dose Aspirin (Prophylaxis)	Initiated at 12–16 weeks in high-risk women, reduces preeclampsia incidence by ~17% (ASPRE trial); inexpensive, well-tolerated	Effective only as prophylaxis; ineffective once disease is established; adherence and timing-dependent

Strengths and limitations of major interventions in preeclampsia management

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CLINICAL PEARL

Magnesium sulfate is given for seizure prophylaxis, not for blood pressure control. This is one of the most frequently tested distinctions on board examinations. The mechanism involves NMDA receptor antagonism and cerebral vasodilation, which raises the seizure threshold. Always check deep tendon reflexes, respiratory rate, and urine output to monitor for magnesium toxicity. The therapeutic range is 4–7 mEq/L; loss of patellar reflexes occurs around 8–12 mEq/L, respiratory depression at 12–15 mEq/L, and cardiac arrest above 25 mEq/L. Calcium gluconate (1 g IV) is the antidote.

SECTION 8

Long-Term Cardiovascular Risk & Emerging Research

Although preeclampsia classically resolves after delivery, accumulating epidemiological evidence demonstrates that it is not a self-limited condition from a cardiovascular perspective. Women who experience preeclampsia carry a significantly elevated lifetime risk of chronic hypertension, ischemic heart disease, stroke, and heart failure. The American Heart Association now lists a history of preeclampsia as an independent cardiovascular risk factor. Whether preeclampsia directly injures the vasculature or uncovers a pre-existing endothelial vulnerability remains a subject of active investigation—the so-called 'cause versus marker' debate.

Outcome	After Preeclampsia (Relative Risk)	After Normotensive Pregnancy
Chronic Hypertension	RR ≈ 3.7 (within 15 years)	Baseline population rate
Ischemic Heart Disease	RR ≈ 2.2	Baseline population rate
Stroke	RR ≈ 1.8	Baseline population rate
Heart Failure	RR ≈ 4.2	Baseline population rate
End-Stage Renal Disease	RR ≈ 4.7	Baseline population rate

Long-term cardiovascular and renal outcomes following preeclampsia (meta-analytic estimates)

Emerging Research Directions

sFlt-1 Apheresis: Extracorporeal adsorption columns (e.g., Dextran sulfate cellulose) can selectively remove sFlt-1 from maternal plasma, potentially prolonging gestation in severe early-onset disease. Phase II trials have shown modest extension of pregnancy duration.
Metformin: Preclinical and early clinical data suggest that metformin may reduce sFlt-1 secretion from trophoblasts and improve endothelial function, positioning it as a potential adjunctive therapy for preeclampsia in women with metabolic risk factors.
Pravastatin: Statins upregulate heme oxygenase-1 and PlGF in trophoblasts, counteracting the anti-angiogenic shift. The StAmP trial and ongoing studies are evaluating pravastatin prophylaxis in high-risk pregnancies.
Cell-Free Fetal DNA Screening: Elevated circulating cell-free fetal DNA in the first trimester may predict subsequent preeclampsia, offering a new biomarker for early risk stratification alongside sFlt-1/PlGF ratios and uterine artery Doppler velocimetry.

These innovations reflect a broader shift in the field from reactive management (deliver when severe) toward predictive modeling and upstream intervention. As molecular diagnostics become more accessible, the hope is that preeclampsia will transition from a disease diagnosed at the bedside to one predicted and prevented in the first trimester.

SECTION 9

Practice Problems

Question 1: CONCEPTUAL

Explain why delivery of the placenta is the definitive treatment for preeclampsia. In your answer, identify the specific organ responsible for the disease and describe how its removal resolves the maternal syndrome.

Show answer

Preeclampsia originates from the placenta, which—when ischemic due to defective spiral artery remodeling—releases excessive anti-angiogenic factors (principally sFlt-1 and soluble endoglin) into the maternal circulation. These factors sequester VEGF and PlGF, depriving the maternal endothelium of essential pro-survival signals and causing systemic vasospasm, increased vascular permeability, and end-organ damage. Delivery of the placenta eliminates the source of sFlt-1 and soluble endoglin, allowing circulating VEGF and PlGF levels to normalize. Within 24–48 hours postpartum, endothelial function recovers, blood pressure decreases, proteinuria resolves, and platelet counts rise—though complete normalization may take weeks, and long-term cardiovascular risk persists.

Question 2: BASIC CALCULATION

A patient at 30 weeks of gestation has a serum sFlt-1 level of 8,500 pg/mL and a PlGF level of 45 pg/mL. Calculate the sFlt-1/PlGF ratio. Based on published cutoff values, does this ratio suggest a high or low probability of preeclampsia?

Show answer

The sFlt-1/PlGF ratio is calculated as 8,500 ÷ 45 ≈ 188.9. The clinical cutoff for ruling in a high probability of preeclampsia is an sFlt-1/PlGF ratio ≥ 38 (PROGNOSIS study). A ratio below 38 carries a negative predictive value above 99% for ruling out preeclampsia within one week. For early-onset disease (< 34 weeks), a ratio above 85 is considered strongly indicative. This patient's ratio of approximately 189 far exceeds both thresholds, indicating a very high probability of established preeclampsia. The clinician should proceed with a full workup including CBC, CMP, LDH, and urine protein quantification.

Question 3: INTERMEDIATE

A 34-year-old G3P2 at 28 weeks presents with blood pressure of 172/114 mmHg, platelet count of 68,000/µL, AST of 210 U/L, LDH of 850 IU/L, and schistocytes on peripheral smear. Her creatinine is 0.9 mg/dL, and her 24-hour urine protein is only 180 mg. Can she be diagnosed with preeclampsia despite having subthreshold proteinuria? Justify your answer and identify the specific variant of her disease.

Show answer

Yes, this patient meets the diagnostic criteria for preeclampsia with severe features despite having proteinuria below 300 mg/24 h. According to the 2013 ACOG Task Force Report (reaffirmed in 2020 Practice Bulletin), proteinuria is no longer required for the diagnosis of preeclampsia when other severe features are present. Her severe criteria include: systolic BP ≥ 160 mmHg, thrombocytopenia (platelets < 100,000/µL), and hepatic transaminases more than twice the upper limit of normal. Additionally, the combination of hemolysis (schistocytes, LDH > 600 IU/L), elevated liver enzymes, and low platelets qualifies her for the specific diagnosis of HELLP syndrome, a severe variant of preeclampsia. This case illustrates why clinicians should never wait for proteinuria to make the diagnosis when other organ dysfunction is evident.

Question 4: APPLIED

A primigravid woman with chronic hypertension controlled on labetalol presents at her 12-week prenatal visit. She has a BMI of 36 and a sister who developed preeclampsia at 30 weeks. Her provider considers prescribing low-dose aspirin. Identify all of her risk factors for preeclampsia, explain the pathophysiological rationale for aspirin prophylaxis, and state the recommended dosing regimen.

Show answer

This patient has multiple risk factors: (1) nulliparity (first pregnancy), which is associated with inadequate immune tolerance to paternal antigens at the feto-maternal interface; (2) chronic hypertension, which predisposes to superimposed preeclampsia due to pre-existing endothelial dysfunction; (3) obesity (BMI ≥ 30), which is linked to chronic inflammation, insulin resistance, and heightened oxidative stress—all of which amplify endothelial injury; and (4) a first-degree relative with preeclampsia, indicating possible shared genetic susceptibility related to complement regulation, angiogenic factor polymorphisms, or coagulation pathways. Low-dose aspirin (81–162 mg/day, ideally 150 mg) is recommended by ACOG and USPSTF beginning between 12 and 16 weeks of gestation and continued until delivery. The mechanism involves selective inhibition of thromboxane A₂ synthesis (a vasoconstrictor and platelet aggregator) in platelets while relatively sparing endothelial prostacyclin (PGI₂, a vasodilator), thereby restoring the thromboxane/prostacyclin balance and improving placental perfusion during the critical window of trophoblast invasion.

Question 5: CRITICAL THINKING

Preeclampsia is often described using the 'two-stage model,' but recent evidence suggests that late-onset preeclampsia (≥ 34 weeks) may arise primarily from maternal constitutional factors rather than placental disease. Compare and contrast the proposed pathophysiology of early-onset versus late-onset preeclampsia, discuss how this distinction challenges the two-stage paradigm, and explain the implications for biomarker-based prediction and prevention strategies.

Show answer

The two-stage model (defective placentation → maternal syndrome) best describes early-onset preeclampsia (< 34 weeks), which is strongly associated with abnormal uterine artery Doppler waveforms, intrauterine growth restriction, markedly elevated sFlt-1/PlGF ratios, and histopathological evidence of shallow trophoblast invasion with atherosis of the spiral arteries. In contrast, late-onset preeclampsia often occurs with normal-caliber spiral arteries, appropriate fetal growth, and only modestly elevated sFlt-1/PlGF ratios. The emerging hypothesis is that late-onset disease reflects a 'maternal phenotype' in which pre-existing endothelial vulnerability—driven by metabolic syndrome, obesity, insulin resistance, advanced maternal age, or subclinical cardiovascular disease—interacts with the physiological demands of late pregnancy (expanded blood volume, increased cardiac output) to unmask a hemodynamic mismatch. In this model, the placenta may be 'normal' but the maternal vasculature is incapable of adapting to pregnancy's demands. This distinction challenges the universality of the two-stage model and has practical implications: first-trimester biomarkers (uterine artery pulsatility index, PlGF, PAPP-A) and aspirin prophylaxis are most effective for predicting and preventing early-onset disease, while late-onset disease may be better predicted by maternal risk factor scoring and metabolic markers. Future prevention strategies for late-onset disease may need to target maternal metabolic health rather than placental angiogenesis.

SUMMARY

Preeclampsia — Comprehensive Summary

Summary

Preeclampsia is a pregnancy-specific systemic endothelial disorder arising after 20 weeks of gestation, classically explained by the two-stage model: Stage 1 involves defective trophoblast invasion of the spiral arteries, producing placental ischemia; Stage 2 is the maternal syndrome driven by an angiogenic imbalance (excess sFlt-1 sequestering VEGF and PlGF), resulting in endothelial dysfunction that manifests as hypertension, proteinuria, and multi-organ injury.

The disorder is classified by severity (without severe features versus with severe features) and by timing (early-onset < 34 weeks versus late-onset ≥ 34 weeks). Management hinges on magnesium sulfate for seizure prophylaxis, antihypertensives (labetalol, hydralazine, nifedipine) for acute blood pressure control, antenatal corticosteroids for fetal lung maturation in preterm cases, and delivery as the definitive cure. The sFlt-1/PlGF ratio serves as a powerful biomarker for diagnosis and short-term prediction. Critically, a history of preeclampsia confers long-term cardiovascular risk, warranting lifelong surveillance and risk factor modification. Low-dose aspirin prophylaxis beginning at 12–16 weeks remains the most effective preventive strategy for high-risk women.