Hypertension in pregnancy
Exam Tips
- Diagnose pre-eclampsia as new hypertension after 20 weeks plus proteinuria and/or maternal organ dysfunction or uteroplacental dysfunction; proteinuria is not mandatory if other end-organ features are present.
- In OSCE stations, state the severe BP threshold (>=160 systolic or >=110 diastolic) and explicitly mention urgent antihypertensive treatment to reduce maternal stroke risk.
- Remember progression risk: gestational hypertension presenting earlier in pregnancy is more likely to evolve into pre-eclampsia.
- Always include fetal assessment (growth scan, amniotic fluid, Doppler, CTG when indicated) as part of maternal hypertension work-up.
- Name key contraindicated drugs in pregnancy: ACE inhibitors, ARBs, and aliskiren.
- See figure of maternal-fetal consequences in hypertensive disorders (placental malperfusion -> fetal growth restriction, placental abruption, prematurity) in core obstetric revision atlases.
Definition
Hypertension in pregnancy is a spectrum of disorders defined by elevated blood pressure during gestation, including chronic hypertension (present before pregnancy or before 20 weeks), gestational hypertension (new after 20 weeks without significant proteinuria), and pre-eclampsia (new hypertension after 20 weeks with proteinuria and/or maternal organ or uteroplacental dysfunction). In UK practice, hypertension is generally BP 140/90-159/109 mmHg and severe hypertension is BP at or above 160/110 mmHg, which requires urgent assessment and treatment.
Pathophysiology
Pre-eclampsia is primarily a placental-endothelial disorder: abnormal trophoblastic invasion and inadequate spiral artery remodelling lead to high-resistance uteroplacental flow, placental ischaemia, and release of anti-angiogenic/inflammatory factors (for example increased sFlt-1 and reduced PlGF activity). This causes widespread maternal endothelial dysfunction, vasoconstriction, capillary leak, platelet activation, and end-organ injury (kidney, liver, brain, coagulation system). Gestational hypertension may represent a milder phenotype of the same vascular maladaptation, while chronic hypertension reflects pre-existing vascular disease that increases risk of superimposed pre-eclampsia. See figure of failed spiral artery remodelling in standard obstetric pathology diagrams.
Risk Factors
- Previous hypertensive disorder of pregnancy (especially prior pre-eclampsia)
- Chronic hypertension
- Chronic kidney disease
- Autoimmune disease (systemic lupus erythematosus or antiphospholipid syndrome)
- Type 1 or type 2 diabetes
- Nulliparity (first pregnancy)
- Maternal age 40 years or older
- BMI 35 kg/m2 or greater at booking
- Multiple pregnancy
- Family history of pre-eclampsia
- Interpregnancy interval greater than 10 years
- Black ethnicity
- Low socioeconomic status
- History of placental disease (for example placental abruption or stillbirth)
Clinical Features
Symptoms
- Persistent severe headache, often not relieved by simple analgesia
- Visual disturbance (blurred vision, flashing lights, scotomata, photophobia)
- Epigastric or right upper quadrant pain
- Nausea and vomiting
- Breathlessness (possible pulmonary oedema)
- Sudden swelling of face, hands, or feet
- Reduced fetal movements (possible uteroplacental insufficiency)
Signs
- Blood pressure 140/90 mmHg or higher (severe if 160/110 mmHg or higher)
- Proteinuria (dipstick 2+ or raised PCR/ACR)
- Hyperreflexia or clonus in severe disease
- Generalized oedema (supportive, not diagnostic alone)
- Neurological deficit or seizure in eclampsia
- Features of fetal growth restriction (small-for-gestational-age uterus/fetus)
Investigations
Management
Lifestyle Modifications
- Shared obstetric-physician care with frequent BP and symptom surveillance, plus clear safety-net advice for headache, visual symptoms, RUQ pain, breathlessness, or reduced fetal movements
- Home BP monitoring where appropriate, with escalation thresholds agreed in writing
- Smoking cessation, avoidance of alcohol/recreational drugs, and healthy pregnancy diet and activity
- Aspirin prophylaxis for women at high risk of pre-eclampsia: aspirin 75-150 mg once nightly from 12 weeks until birth (unless contraindicated)
Pharmacological Treatment
First-line oral antihypertensive
- Labetalol 100 mg twice daily initially, titrate to 200-400 mg twice daily; maximum 2.4 g/day in divided doses
Common UK first choice in pregnancy. Avoid/caution in asthma, bradycardia, second/third-degree heart block, or decompensated heart failure.
Alternative oral antihypertensives
- Nifedipine modified-release 10-40 mg twice daily (or equivalent MR regimen), adjusted to BP response; usual maximum up to 120 mg/day
- Methyldopa 250 mg two to three times daily, titrate as needed; maximum 3 g/day
Use if labetalol not suitable/tolerated. Nifedipine can cause headache/flushing/oedema. Methyldopa can cause sedation, depression, hepatotoxicity, and haemolytic anaemia; monitor LFT/FBC if prolonged use and usually discontinue soon after birth.
Acute severe hypertension (hospital management)
- IV labetalol 20 mg over 2 minutes, then 40-80 mg every 10 minutes as needed (or infusion per protocol), with continuous maternal-fetal monitoring
- Oral immediate-release nifedipine 10 mg, repeat after 20-30 minutes if needed (local protocol dependent)
- IV hydralazine 5-10 mg slowly, repeated per response
Treat urgently to reduce maternal stroke risk. Avoid rapid overcorrection that may compromise placental perfusion.
Seizure prophylaxis/treatment in severe pre-eclampsia or eclampsia
- Magnesium sulfate 4 g IV loading over 5-15 minutes, then 1 g/hour IV infusion for 24 hours (additional 2 g IV for recurrent seizure)
Monitor respiratory rate, urine output, and reflexes; calcium gluconate is antidote for magnesium toxicity.
Drugs to avoid in pregnancy hypertension
- ACE inhibitors (for example enalapril, lisinopril)
- Angiotensin receptor blockers (for example losartan, candesartan)
- Direct renin inhibitor (aliskiren)
Contraindicated in pregnancy due to fetotoxicity (renal dysgenesis, oligohydramnios, skull/lung effects, fetal/neonatal renal failure).
Surgical / Interventional
- Planned delivery (induction of labour or caesarean section) is the definitive treatment for pre-eclampsia when maternal or fetal risk outweighs continuing pregnancy
- Urgent delivery for uncontrolled severe hypertension, eclampsia, HELLP, placental abruption, or non-reassuring fetal status despite stabilization
Complications
- Progression from gestational hypertension to pre-eclampsia (higher risk when onset is earlier in pregnancy)
- Eclampsia (generalized tonic-clonic seizures)
- HELLP syndrome (haemolysis, elevated liver enzymes, low platelets)
- Intracranial haemorrhage and stroke
- Acute kidney injury
- Pulmonary oedema/ARDS
- Liver injury, including subcapsular haematoma or rupture (rare, life-threatening)
- Disseminated intravascular coagulation
- Placental abruption
- Fetal growth restriction and prematurity
- Stillbirth, neonatal morbidity, and increased NICU admission
- Increased long-term maternal risk of chronic hypertension, cardiovascular disease, stroke, and chronic kidney disease
Prognosis
Most women with mild-moderate chronic hypertension have good outcomes with close antenatal care, but approximately one quarter develop superimposed pre-eclampsia. Earlier-onset gestational hypertension (especially before 35 weeks) has a substantially higher chance of progression to pre-eclampsia than late-onset disease. Pre-eclampsia before 34 weeks carries worse maternal-fetal prognosis than later disease, and a history of hypertensive pregnancy disorder increases recurrence risk and future cardiovascular risk in subsequent life.
Sources & References
✅NICE Guidelines(1)
- Hypertension in pregnancy[overview]
📖Textbook References(8)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 537)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 539)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 550, 551)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1748)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 435)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 435)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 435)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 1300)[context]