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Hypertension in Pregnancy

NICE guideline [NG133] Hypertension in pregnancy: diagnosis and management. Last updated: Apr 2023 NICE CKS Hypertension in pregnancy. Last revised: Jan 2025.

Background Information

There are 3 main forms of hypertension in pregnancy:
 
Term Definition
Chronic Hypertension Hypertension present before 20 weeks gestation (or prior to booking visit)
Gestational Hypertension New onset hypertension after 20 weeks gestation without proteinuria
Pre-eclampsia New onset hypertension after 20 weeks gestation AND 1 or more of the following new-onset conditions:
  • Proteinuria
  • Other maternal end-organ dysfunction
    • Renal insufficiency
    • Liver involvement (↑ AST / ALT +/- RUQ or epigastric abdominal pain)
    • Neurological complications (e.g. eclampsia, altered mental status, visual disturbances, clonus, headache)
    • Haematological complications (e.g. thrombocytopaenia, DIC, haemolysis)
    • Uteroplacental dysfunction (e.g. fetal growth restriction, abnormal umbilical artery doppler)


HELLP syndrome: severe form of pre-eclampsia
  • H: Haemolysis
  • EL: Elevated Liver enzymes
  • LP: Low Platelet

Eclampsia: occurrence of seizure in a women with pre-eclampsia (usually generalised tonic-clonic)

  • Nulliparity
  • Multiple pregnancy.
  • Black ethnicity.
  • Maternal obesity.
  • Maternal type 1 diabetes.

High risk factors
  • Hypertension in previous pregnancy
  • Chronic hypertension
  • Diabetes (type I / II)
  • Chronic kidney disease
  • Autoimmune disease (e.g. SLE, antiphospholipid syndrome)
Moderate risk factors
  • Family history of pre-eclampsia
  • First pregnancy
  • Multiple pregnancy
  • Pregnancy interval >10 years
  • ≥40 y/o
  • BMI ≥35 kg/m2
Other risk factors
  • Black ethnicity
  • Low socioeconomic status
  • History of stillbirth / placental abruption
  • Gestational hypertension

Pre-Eclampsia Prevention Guidelines

Aspirin 75-150mg from 12 weeks until birth is indicated if:
  • 1 or more high risk factor, or
  • 2 or more moderate risk factors

Pre-eclampsia risk factors:
 
High risk factors
  • Hypertension in previous pregnancy
  • Chronic hypertension
  • Diabetes (type I / II)
  • Chronic kidney disease
  • Autoimmune disease (e.g. SLE, antiphospholipid syndrome)
Moderate risk factors
  • Family history of pre-eclampsia
  • First pregnancy
  • Multiple pregnancy
  • Pregnancy interval >10 years
  • ≥40 y/o
  • BMI ≥35 kg/m2
 

Apart from aspirin, NICE states NOT to recommend any of the following to prevent hypertensive disorders during pregnancy without any other indications:

  • Other pharmacological agents (low molecular weight heparin, diuretics, progesterone, nitric oxide donors)
  • Nutritional supplements (magnesium, folic acid, vitamin C and E, fish oils, algal oils, garlic)
  • Salt restriction diet
  • Specific lifestyle changes (i.e. give the same advise as other healthy pregnant women)

Hypertensive Disorder Guidelines

The following anti-hypertensive medications should be stopped:
  • ACE inhibitor and ARB
  • Thiazide and thiazide-like diuretics

Calcium channel blockers are safe in pregnancy.

 

Most patients with chronic hypertension is likely to be taking a statin as well, statins should also be stopped prior pregnancy.

Blood pressure target: 135/85 mmHg

Offer additional anti-hypertensive treatment if BP ≥140/90 mmHg:
  • 1st line: labetalol
  • 2nd line: nifedipine
  • 3rd line: methyldopa

 

As mentioned above, chronic hypertension is an indication for pre-eclampsia prevention - 75-150mg aspirin from 12 weeks until birth.

Chronic hypertension alone is NOT an indication for early birth before 37 weeks.

  • If methydopa is started → stop within 2 days and change to an alternative 
  • Monitor blood pressure
    • Daily for first 2 days
    • At least once between day 3-5
  • Review 6-8 weeks after birth 

Admit if BP >160/110 mmHg

Blood pressure target: 135/85 mmHg

Offer anti-hypertensive treatment if BP ≥140/90 mmHg:
  • 1st line: labetalol
  • 2nd line: nifedipine
  • 3rd line: methyldopa

Gestational hypertension alone is NOT an indication for early birth before 37 weeks.

  • If methydopa is started → stop within 2 days and change to an alternative 
  • Monitor blood pressure
    • Daily for first 2 days
    • At least once between day 3-5
  • Review 6-8 weeks after birth (if remain on anti-hyerptensive treatment, review 2 weeks after)

For those that did not take antihypertensive treatment and have given birth, start antihypertensive treatment if BP ≥150/100 mmHg.

Offer PLFGPlacental Growth Factor-based testing at 20-36+6 weeks to exclude pre-eclampsia if suspected (e.g. chronic hypertension and gestational hypertension):

  • Low indicates high risk of pre-eclampsia
  • High indicates low risk

Offer hospital admission if any of the following:
  • Systolic BP ≥160 mmHg
  • Abnormal blood tests
    • ↑ Creatinine (≥90 mmol/L)
    • ↑ ALT (2x of upper limit normal range / >70 IU/L)
    • ↓ Platelet (<150,000)
  • Signs of impending pulmonary oedema
  • Signs of s evere pre-eclampsia
  • Suspected fetal compromise
  • Signs of impending eclampsia

Blood pressure target: 135/85 mmHg
Offer anti-hypertensive treatment if BP ≥140/90 mmHg:
  • 1st line: labetalol
  • 2nd line: nifedipine
  • 3rd line: methyldopa

Initiate birth within 24-48 hours once 37 weeks onwards.

Only consider early birth before 37 weeks if any of the following:
  • Inability to control BP despite 3 classes of medication
  • SpO2 <90%
  • Progressive deterioration in liver function / renal function / haemolysis / platelet count
  • Ongoing neuroloigcal features (e.g. severe headache, repeated visual disturbances, eclampsia)
  • Placental abruption
  • Reversed end-diastolic flow in umbilical artery doppler / non-reassuring CTG / still birth 

  • If methydopa is started → stop within 2 days and change to an alternative 
  • Monitor blood pressure
    • If women did NOT take anti-hypertensive treatment
      • At least 4 times a day while in patient
      • At least once between day 3-5 (if abnormal on day 3-5 → alternate days until normal)
    • If women took anti-hypertensive treatment
      • At least 4 times a day while in patien t
      • Every 1-2 days for up to 2 weeks until off tratment and no hypertension
  • Review 6-8 weeks after birth (if remain on anti-hyerptensive treatment, review 2 weeks after)

For those that did not take antihypertensive treatment and have given birth, start antihypertensive treatment if BP ≥150/100 mmHg.

Tests for fetal monitoring:
  • Ultrasound - assess fetal growth and amniotic fluid volume assessment
  • Umbilical artery doppler
  • Cardiotocography - assess fetal wellbeing 

Hypertensive disorder Test Frequency
Chronic hypertension Ultrasound At 28, 32, 36 weeks
Umbilical artery doppler
Gestational hypertension Ultrasound At diagnosis
Then, repeat every 2-4 weeks (if normal)
Umbilical artery doppler
Pre-eclampsia / severe gestational hypertension (≥160/110 mmHg) Cardiotocography  At diagnosis (no need routine repeat after)
 
  Ultrasound At diagnosis,
Then every 2 weeks
  Umbilical artery doppler
 

Apart from pre-eclampsia / severe gestational hypertension, there is no need for routine cardiotocography, unless clinically indicated.

Eclampsia Guidelines

Give IV magnesium sulfate immeidately if eclampsia develops (i.e. if a seizure develops in someone with pre-eclampsia).

Consider giving magnesium sulfate if 1 or more of the following severe pre-eclampsia feature is present:
  • Ongoing or recurring severe headaches
  • Visual scotomata
  • Nausea or vomiting
  • Epigastric pain
  • Oliguria and severe hypertension (≥160/110 mmHg)
  • Progressive deterioration in laboratory blood tests (e.g. rising creatinine or liver transaminases, or falling platelet count)

NICE recommends the Collaborative Eclampsia Trial regimen:
  • Loading dose: IV 4g over 5-15 min
  • Maintenance: 1g/hour for 24 hours + to be continued for 24 hours after last fit

For recurrent fits: give further dose of 2-4g of IV magnesium sulfate over 5-15 min

 

Do not use diazepam, phenytoin or other anticonvulsants as an alternative to magnesium sulfate in women with eclampsia.

Treat severe hypertension (≥160/110 mmHg) with any of the following:
  • Labetalol (oral / IV)
  • Oral nifedipine
  • IV hydralazine

Anti-Hypertensive Treatment During Postnatal Period

1st line:
  • Enalapril
  • If black Afro-Caribbean → nifedipine / amlodipine

2nd line: enalapril + nifedipine / amlodipine

3rd line: 
  • Add atenolol / labetalol to enalapril + nifedipine / amlodipine, or
  • Swap 1 medication to atenolol / labetalol
 

NICE recommends to AVOID using diuretics and ARBs to treat hypertension in the postnatal period who are breastfeeding / expressing milk.

 

NICE recommends to explain to brestfeeding women that:
  • Anti-hypertensive drugs CAN pass into breast milk
  • Most only lead to very low levels in breast milk, therefore amounts taken in by babies are very small and unlikely to have any clinical effect
  • Most medicines are not tested in pregnant or breastfeeding women, so disclaimers in the manufacturer's information are not because of any specific safety concerns or evidence of harm

References

Author: Adams Lau
Reviewer: 
Last edited: 04/07/25