Hypertension in Pregnancy

Classification

• Chronic hypertension: present before 20 weeks or pre-existing diagnosis
• Gestational hypertension: new hypertension after 20 weeks without proteinuria or other features of pre-eclampsia
• Pre-eclampsia: new hypertension after 20 weeks with significant proteinuria (urine PCR ≥30 mg/mmol) OR other maternal organ dysfunction

Blood Pressure Thresholds

• Mild: systolic 140-149 mmHg OR diastolic 90-99 mmHg
• Moderate: systolic 150-159 mmHg OR diastolic 100-109 mmHg
• Severe: systolic ≥160 mmHg OR diastolic ≥110 mmHg

Aspirin Prophylaxis

• Aspirin 150mg daily from 12 weeks to 36 weeks (taken at bedtime)
• Indicated if any ONE high-risk factor:
  • Previous pre-eclampsia
  • Chronic kidney disease
  • Autoimmune disease (SLE, antiphospholipid syndrome)
  • Type 1 or type 2 diabetes
  • Chronic hypertension
• Indicated if TWO or more moderate-risk factors:
  • First pregnancy
  • Age ≥40
  • BMI ≥35
  • Family history of pre-eclampsia (first-degree relative)
  • Multiple pregnancy
  • Interpregnancy interval >10 years

PlGF-Based Testing

• Placental growth factor (PlGF) testing recommended from 20 weeks when pre-eclampsia is suspected
• Low PlGF (<100 pg/ml before 35 weeks): high sensitivity for pre-eclampsia requiring delivery within 14 days
• Normal PlGF: high negative predictive value — helps rule out pre-eclampsia
• sFlt-1:PlGF ratio >38: suggests pre-eclampsia likely
• Aids clinical decision-making — does not replace clinical assessment

Antihypertensive Treatment

Chronic Hypertension

• Stop ACE inhibitors and ARBs before conception or as soon as pregnancy confirmed (teratogenic)
• Switch to labetalol, nifedipine MR, or methyldopa
• Target BP <135/85 mmHg

Gestational Hypertension and Pre-eclampsia

• Treat if BP reaches moderate threshold (≥150/100)
• First-line: labetalol (contraindicated in asthma)
• Second-line: nifedipine MR
• Third-line: methyldopa (avoid postnatally due to depression risk)
• Acute severe hypertension: IV labetalol or oral nifedipine 10mg immediate-release
• Target: <135/85 mmHg

Monitoring

Gestational Hypertension

• BP twice weekly, weekly bloods (FBC, LFTs, U&E), weekly urine PCR
• USS for fetal growth at diagnosis, 28, 32, 36 weeks

Pre-eclampsia

• More frequent monitoring (3 times/week BP, twice weekly bloods)
• Consider admission if severe features
• Continuous CTG if acute presentation
• Daily fetal assessment (CTG, Doppler) if admitted

Timing of Birth

• Chronic hypertension (uncomplicated): aim for 37-38+6 weeks
• Gestational hypertension (uncomplicated): aim for 37-38+6 weeks
• Pre-eclampsia: offer delivery at 37+0 weeks
• Pre-eclampsia with severe features: stabilise and deliver; <34 weeks with severe features — corticosteroids before delivery, individualise timing
• Eclampsia or HELLP: stabilise and deliver regardless of gestation

Postpartum Management

• Continue monitoring BP for minimum 5 days postnatally
• BP may rise on days 3-6 postpartum
• Enalapril: first-line postnatal antihypertensive (safe in breastfeeding)
• Stop methyldopa within 2 days of delivery
• Target BP <140/90 in first 6 weeks
• Postnatal review at 6-8 weeks: BP check, discuss long-term cardiovascular risk
• Pre-eclampsia doubles lifetime risk of cardiovascular disease

Important Facts for MRCOG

• Aspirin 150mg at bedtime from 12 weeks for high-risk women
• ACE inhibitors/ARBs: teratogenic — discontinue before conception
• Treat at moderate threshold (≥150/100), not just severe
• PlGF testing from 20 weeks aids pre-eclampsia diagnosis
• Labetalol first-line (avoid in asthma)
• Target BP <135/85 in pregnancy
• Enalapril first-line postnatally
• Stop methyldopa within 2 days of delivery
• Pre-eclampsia doubles lifetime CVD risk

Source: NICE NG133 (2023)

Read the original on nice.org.uk

Clinically reviewed by NHS obstetricians and gynaecologists · Source last updated 2023

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