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 75–150 mg daily from 12 weeks until the birth of the baby
• 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

• Offer treatment if BP remains above 140/90 (lowered from 150/100 in 2019)
• 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 75–150 mg daily from 12 weeks until birth: one high-risk factor, or more than one moderate-risk factor
• ACE inhibitors/ARBs: teratogenic — discontinue before conception
• Treat gestational hypertension and pre-eclampsia if BP remains above 140/90 (not 150/100, the pre-2019 threshold)
• 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 (17 April 2023 (published 25 June 2019))

Read the original on nice.org.uk

Clinically reviewed by NHS obstetricians and gynaecologists · Source last updated 17 April 2023 (published 25 June 2019)

MRCOG AI is an independent educational tool. It is not affiliated with, endorsed by, or connected to the Royal College of Obstetricians and Gynaecologists (RCOG).