Pre-Eclampsia — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Pre-eclampsia is a multi-system pregnancy-specific disorder defined by new-onset hypertension (systolic BP 140 mmHg or above, or diastolic BP 90 mmHg or above on two occasions at least 4 hours apart) developing after 20 weeks of gestation, accompanied by proteinuria (300mg protein in 24 hours, or protein:creatinine ratio above 30 mg/mmol) and/or evidence of maternal organ dysfunction (renal, hepatic, haematological, neurological) or uteroplacental dysfunction (fetal growth restriction). Pre-eclampsia affects 2-8% of all pregnancies worldwide and is a leading cause of maternal mortality (responsible for approximately 76,000 maternal deaths annually) and perinatal morbidity and mortality. It can progress to eclampsia (tonic-clonic seizures), HELLP syndrome (haemolysis, elevated liver enzymes, low platelets), and multiorgan failure. Delivery is the only definitive cure. This condition requires careful clinical evaluation and individualised management planning to achieve the best possible outcomes for patients. Healthcare professionals should adopt a comprehensive, evidence-based multidisciplinary approach to both diagnosis and long-term treatment, ensuring patients receive thorough education about their condition, the full range of available treatment options, expected outcomes, and the importance of regular monitoring and follow-up appointments.

Pre-eclampsia arises from abnormal placentation in early pregnancy — shallow, inadequate spiral artery remodelling by extravillous trophoblasts results in a high-resistance, poorly perfused placenta. This triggers widespread maternal endothelial dysfunction through circulating anti-angiogenic factors (particularly elevated soluble fms-like tyrosine kinase-1 — sFlt-1, and reduced placental growth factor — PlGF) and inflammatory mediators. Risk factors — high risk (one of these indicates high-risk): previous pre-eclampsia, chronic kidney disease, autoimmune disease (SLE, antiphospholipid syndrome), type 1 or 2 diabetes, chronic hypertension. Moderate risk (two or more needed): first pregnancy, BMI above 35 at booking, age above 40, family history of pre-eclampsia, multiple pregnancy, interpregnancy interval above 10 years. Additional factors: Black ethnicity (2x higher risk), assisted reproduction, placental pathology. Parous women with a new partner have near-primigravid risk — supporting the role of immune maladaptation.

Maternal symptoms of pre-eclampsia (require urgent assessment): severe headache (persistent, frontal — not relieved by paracetamol), visual disturbances (flashing lights, blurred vision, scotoma — indicating cerebral vasospasm), epigastric or right upper quadrant pain (liver capsule distension — sentinel symptom of HELLP), nausea and vomiting in the second half of pregnancy, sudden swelling of face, hands, and feet (more rapid than expected), and reduced fetal movements (indicating fetal compromise from placental insufficiency). Many women with pre-eclampsia are asymptomatic — hypertension detected only at routine antenatal blood pressure measurement. Severe features indicating imminent danger: BP 160/110 or above, severe headache, visual disturbance, epigastric pain, papilloedema, hyperreflexia with clonus, oliguria (urine output below 25ml/hour), pulmonary oedema. Eclampsia: tonic-clonic seizures occurring in a woman with pre-eclampsia (or occasionally without prior warning).

Blood pressure measurement: automated validated oscillometric device (or manual mercury sphygmomanometer) with correct cuff size; 140/90 mmHg or above on two readings 4+ hours apart confirms hypertension. Urinalysis: protein:creatinine ratio (PCR) — PCR above 30 mg/mmol (or 24-hour urine protein above 300mg) confirms significant proteinuria; automated dipstick 1+ or above warrants formal protein quantification. Blood tests: FBC (thrombocytopaenia — platelets below 150x10^9/L suggests HELLP), U&E (creatinine elevation — renal impairment), LFTs (elevated ALT/AST — hepatic involvement), uric acid (raised in pre-eclampsia), coagulation screen. Placental growth factor (PlGF) testing: PlGF below 100 pg/mL (or PlGF:sFlt-1 ratio) distinguishes pre-eclampsia from other hypertensive disorders — sensitive and specific biomarker; NICE recommends sFlt-1/PlGF ratio testing between 20-34+6 weeks when pre-eclampsia suspected. Fetal wellbeing assessment: ultrasound for fetal growth, amniotic fluid volume, umbilical artery Doppler (absent or reversed end-diastolic flow indicates severe uteroplacental insufficiency), CTG monitoring.

Delivery is the only definitive cure — timing depends on gestational age and severity. Before 34 weeks: maternal and fetal monitoring in a consultant-led unit; antenatal corticosteroids (betamethasone 2 doses 24 hours apart) to mature fetal lungs if delivery anticipated before 34 weeks. At 34-37 weeks: delivery is generally planned if severe features present or deteriorating despite treatment. At 37 weeks or above: delivery recommended regardless of severity. Antihypertensive therapy for BP 150/100 or above to reduce maternal stroke risk: Oral/IV labetalol (first-line — avoid in asthma), oral nifedipine modified-release, IV hydralazine. Target BP 135/85 mmHg or below (avoid hypotension — jeopardises placental perfusion). Magnesium sulphate is the treatment and prevention of eclamptic seizures: loading dose 4g IV over 5-10 minutes, then maintenance 1g/hour IV infusion for 24 hours; reduces eclampsia risk by 58% (Magpie Trial). Anticonvulsants (diazepam, phenytoin) are inferior to magnesium and should not be used. HELLP syndrome: prompt delivery; platelet transfusion if platelets below 50x10^9/L and bleeding; dexamethasone (controversial). Fluid management: restrict to avoid pulmonary oedema (a common cause of maternal death).

Eclampsia: tonic-clonic seizures in a woman with pre-eclampsia (or within 24 hours of delivery) — a life-threatening obstetric emergency; occurs in approximately 1-2% of pre-eclampsia cases; requires immediate IV magnesium sulphate, airway protection, and urgent delivery; associated with maternal stroke, aspiration pneumonia, and neonatal hypoxia. HELLP syndrome (Haemolysis, Elevated Liver enzymes, Low Platelets): the most severe hepatic complication — affects 10-20% of severe pre-eclampsia cases; presents with right upper quadrant or epigastric pain (90%), malaise, and nausea; risks include hepatic rupture (0.2% — catastrophic haemorrhage), placental abruption (16%), acute renal failure, and disseminated intravascular coagulation (DIC). Acute kidney injury: creatinine elevation above 90 micromol/L from glomerular endotheliosis and impaired renal perfusion; severe cases may progress to acute tubular necrosis requiring dialysis. Pulmonary oedema: a common cause of maternal death in pre-eclampsia — excessive IV fluid administration or reduced albumin oncotic pressure from proteinuria drives alveolar flooding; requires urgent furosemide and oxygen, and is a contraindication to further aggressive fluid resuscitation. Placental abruption: uteroplacental insufficiency and decidual vasculopathy increase the risk of premature placental separation — causes fetal hypoxia, stillbirth, and maternal haemorrhage. Fetal and neonatal complications: intrauterine growth restriction (IUGR) from placental insufficiency, iatrogenic preterm birth (the most common neonatal complication — respiratory distress syndrome, necrotising enterocolitis, intraventricular haemorrhage from prematurity), and stillbirth in severe or untreated disease. Long-term maternal cardiovascular risk: women who have had pre-eclampsia have a 2-4x increased lifetime risk of hypertension, ischaemic heart disease, and stroke — warranting annual blood pressure, lipid, and glucose screening after delivery.

Low-dose aspirin (75-150mg daily, initiated between 11-16 weeks) is the most effective pharmacological prevention measure in women at high risk of pre-eclampsia — reduces early-onset pre-eclampsia by 62% and pre-eclampsia overall by 20-25% (ASPRE trial showed 150mg aspirin reduces preterm pre-eclampsia by 62%). NICE recommends 75mg aspirin for women with one high-risk or two moderate-risk factors. Calcium supplementation (1.5-2g elemental calcium daily) reduces pre-eclampsia risk in women with low calcium intake (common in low-income countries). Optimal management of pre-existing conditions before pregnancy (hypertension, diabetes, SLE, antiphospholipid syndrome) reduces risk. Maintain healthy BMI before pregnancy — obesity is a major modifiable risk factor. Regular antenatal care with BP monitoring enables early detection. First-trimester combined screening (11-14 weeks): uterine artery Doppler + MAP + PlGF + PAPP-A can identify over 75% of early-onset pre-eclampsia for targeted aspirin prophylaxis.

Go to the maternity assessment unit immediately (do not wait for a GP appointment) for: severe headache not relieved by paracetamol, visual disturbances (flashing lights, blurred vision, or vision loss), epigastric or upper abdominal pain, sudden facial or hand swelling, feeling unwell after 20 weeks of pregnancy, or reduced fetal movements. These may indicate severe pre-eclampsia or HELLP syndrome requiring urgent assessment and possible emergency delivery. If a pregnant woman has a seizure, call emergency services immediately — this is eclampsia. Do not delay seeking help. Women with diagnosed pre-eclampsia who have been sent home should seek immediate reassessment if symptoms worsen between scheduled visits.