About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Definition: new hypertension (≥140/90) after 20 weeks + significant proteinuria (PCR ≥30) or organ dysfunction
- Risk factors: first pregnancy, age >40, BMI >35, previous pre-eclampsia, chronic HTN, CKD, autoimmune disease, multiple pregnancy
- Prevention: aspirin 150 mg from 12 weeks in high-risk women (NICE recommended)
- Treatment: labetalol first-line antihypertensive. IV MgSO₄ for seizure prophylaxis if severe features
- Definitive treatment: DELIVERY. Timing depends on severity — aim for 37 weeks if possible, deliver immediately if severe/eclampsia
- Eclampsia = pre-eclampsia + seizures. HELLP = Haemolysis, Elevated Liver enzymes, Low Platelets
Overview
Pre-eclampsia is a pregnancy-specific multisystem disorder characterised by new-onset hypertension after 20 weeks of gestation with proteinuria or evidence of maternal organ dysfunction. The underlying pathology is abnormal placentation leading to placental ischaemia, endothelial dysfunction, and a systemic inflammatory response. It complicates 2–8% of pregnancies and remains a leading cause of maternal and perinatal morbidity and mortality worldwide. The only definitive treatment is delivery of the placenta.
Epidemiology
Pre-eclampsia affects 2–8% of pregnancies globally. In the UK, hypertensive disorders are the second leading cause of direct maternal death. Risk factors include nulliparity, previous pre-eclampsia, family history, extremes of maternal age, obesity, chronic hypertension, CKD, diabetes, autoimmune conditions (SLE, antiphospholipid syndrome), and multiple pregnancy. Pre-eclampsia is more common in first pregnancies and with new paternity.
Clinical Features
Symptoms
Often asymptomatic — detected at routine antenatal appointments
Headache — persistent, frontal, not relieved by simple analgesia
Visual disturbance — blurred vision, flashing lights, scotomata
Epigastric or right upper quadrant pain (liver capsule distension — HELLP)
Sudden oedema (face, hands — rapid onset)
Nausea and vomiting (new onset in third trimester)
Seizures (eclampsia)
Signs
Hypertension: BP ≥140/90 (severe: ≥160/110)
Proteinuria on dipstick or urine PCR ≥30 mg/mmol
Brisk reflexes, clonus (indicates cerebral irritability — eclampsia risk)
Oedema (facial, pedal — non-specific, but rapidly progressive suggests pre-eclampsia)
RUQ tenderness (liver involvement)
IUGR on ultrasound (placental insufficiency)
Investigations
First-line
BP measurement≥140/90 on two occasions ≥4 h apart (or single ≥160/110 = severe)
Urine PCR or 24-hour urine proteinPCR ≥30 mg/mmol confirms significant proteinuria. Dipstick ≥1+ requires quantification
BloodsFBC (platelets — low in HELLP), U&Es (creatinine rising), LFTs (transaminases rising in HELLP), uric acid (raised in pre-eclampsia)
Second-line
PlGF-based testingPlacental growth factor (PlGF) — low levels (<12 pg/mL) indicate severe pre-eclampsia with high NPV. NICE recommends from 20 weeks if suspected
CTGFetal monitoring — assess fetal wellbeing
UltrasoundFetal growth, liquor volume, umbilical artery Doppler — assess for IUGR and placental insufficiency
Specialist
Coagulation screenIf HELLP suspected or platelets falling — DIC may develop
1
Prevention
- Aspirin 150 mg OD from 12 weeks to 36 weeks in high-risk women (previous pre-eclampsia, chronic HTN, CKD, autoimmune, diabetes, multiple pregnancy)
- If ≥2 moderate risk factors: also offer aspirin (nulliparity, age >40, BMI >35, FH, pregnancy interval >10 years)
2
Antihypertensive treatment
- Labetalol is first-line (oral for moderate; IV for severe)
- If labetalol contraindicated (asthma): nifedipine MR
- Third-line: methyldopa
- Target BP: <135/85 mmHg
- ACEi/ARB are CONTRAINDICATED in pregnancy — teratogenic
3
Severe pre-eclampsia / eclampsia prevention
- IV magnesium sulphate: for seizure prophylaxis if severe features (BP ≥160/110, symptoms, HELLP)
- Loading dose: 4 g IV over 5–15 min. Maintenance: 1 g/h IV for 24 h
- Monitor: reflexes (loss of patellar reflex = toxicity), respiratory rate (>12), urine output (>25 mL/h)
- Antidote for MgSO₄ toxicity: IV calcium gluconate 10%
4
Delivery — the definitive treatment
- Mild pre-eclampsia without severe features: aim for delivery at 37 weeks
- Severe pre-eclampsia: deliver once the mother is stabilised — timing depends on gestation
- <34 weeks: give antenatal corticosteroids (betamethasone) for fetal lung maturity
- Eclampsia or uncontrollable severe HTN: deliver regardless of gestation after stabilisation
- HELLP syndrome: deliver after stabilisation — DIC and hepatic rupture are life-threatening
Complications
- Eclampsia: Tonic-clonic seizures — treat with IV MgSO₄ (not diazepam or phenytoin)
- HELLP syndrome: Haemolysis, Elevated Liver enzymes, Low Platelets — variant of severe pre-eclampsia with high mortality
- Placental abruption: Premature separation of the placenta — causes antepartum haemorrhage
- DIC: Disseminated intravascular coagulation — consumptive coagulopathy
- Cerebrovascular haemorrhage: From severe hypertension — leading cause of maternal death in pre-eclampsia
- Fetal: IUGR, prematurity, stillbirth
- Long-term: Increased maternal cardiovascular risk in later life
UKMLA Exam Tips
- 1Pre-eclampsia = new HTN after 20 weeks + proteinuria/organ dysfunction. If before 20 weeks → think molar pregnancy
- 2Labetalol = first-line antihypertensive in pregnancy. ACEi/ARB are CONTRAINDICATED
- 3IV MgSO₄ for seizure prophylaxis in severe pre-eclampsia AND for treating eclamptic seizures (NOT phenytoin, NOT diazepam)
- 4MgSO₄ toxicity: loss of reflexes → respiratory depression → cardiac arrest. Antidote = IV calcium gluconate
- 5Aspirin 150 mg from 12 weeks prevents pre-eclampsia in high-risk women — commonly tested prescribing question
- 6HELLP is a variant of severe pre-eclampsia — RUQ pain + deranged LFTs + low platelets + haemolysis
- 7The only CURE for pre-eclampsia is delivery of the placenta — all other treatment is temporising
practicetest your knowledge on pre-eclampsiaApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — obstetrics and beyond.
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