Background Information

Definition

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 characterised by:

• H: Haemolysis
• EL: Elevated Liver enzymes
• LP: Low Platelet

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

Risk Factors

Gestational Hypertension Risk Factors

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

Pre-eclampsia Risk Factors

High risk factors	Hypertension in a 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

Indication

Aspirin 75-150 mg from 12 weeks until birth (to prevent pre-elcampsia) is indicated if:

• 1 or more high-risk factors, or
• 2 or more moderate risk factors

Pre-eclampsia risk factors:

High risk factors	Hypertensive disorder 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

Hypertensive Disorder Guidelines

Chronic Hypertension

Change to Pre-Existing Treatment

The following anti-hypertensive medications should be stopped:

• ACE inhibitor and ARB
• Thiazide and thiazide-like diuretics

Calcium channel blockers are safe in pregnancy.

Management

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

Timing of Birth

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

Gestational Hypertension

Admission Criteria

Admit if BP ≥160/110 mmHg

Management

Blood pressure target: 135/85 mmHg

Offer anti-hypertensive treatment if BP ≥140/90 mmHg:

• 1st line: labetalol
• 2nd line: nifedipine
• 3rd line: methyldopa

Timing of Birth

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

Post-Natal Management

• 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 remaining on anti-hypertensive treatment, review 2 weeks after)

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

Pre-Eclampsia

Testing

Offer PLFG-based testing (maternal blood test) at 20-36⁺⁶ weeks to exclude pre-eclampsia if suspected

• Low (marked decrease) → high risk of pre-eclampsia
• High → low risk (consider alternative Dx)

Management

Admission Criteria

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 severe pre-eclampsia
• Suspected fetal compromise
• Signs of impending eclampsia

Choice of Anti-Hypertensive Agent

Same as gestational hypertension:

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

Magnesium Therapy

Consider giving magnesium sulfate (for eclampsia prophylaxis) if at least 1 of the following severe pre-eclampsia features 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)

Timing of Birth

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 neurological features (e.g. severe headache, repeated visual disturbances, eclampsia)
• Placental abruption
• Reversed end-diastolic flow in umbilical artery doppler / non-reassuring CTG / still birth

Fetal Monitoring

Tests

Tests for fetal monitoring:

• Ultrasound – assess fetal growth and amniotic fluid volume assessment
• Umbilical artery doppler
• Cardiotocography – assess fetal wellbeing

Monitoring Frequency

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 for routine repeat after)
	Ultrasound	At diagnosis, Then every 2 weeks
	Umbilical artery doppler

Eclampsia Guidelines

Seizure Management

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

 

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 the last fit
• For recurrent fits: give a further dose of 2-4g of IV magnesium sulfate over 5-15 min

Anti-Hypertensive Treatment

Treat severe hypertension (≥160/110 mmHg) with any of the following:

• Labetalol (oral / IV)
• Oral nifedipine
• IV hydralazine

Definitive Management

Definitive management of eclampsia is:

• First, stabilise the mother (by treating the seizure and hypertension)
• Then, deliver the baby (once the mother is stabilised)

Post-natal Management

Monitoring and Follow-Up

• Monitor blood pressure
  • Gestational hypertension → daily during day 1-3
  • Pre-eclampsia → 4 times a day while inpatient
• Review 6-8 weeks after birth

Choice of Antihypertensives

If methyldopa is started during pregnancy → stop it within 2 days and change back to conventional anti-hypertensive drugs, see below for choice.

Breastfeeding or Planning to Breastfeed

Breastfeeding is NOT a contraindication for anti-hypertensive therapy. The following is recommended for hypertensive patients:

• 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

Not Breastfeeding or Planning to Breastfeed

Hypertension is treated as per standard NICE hypertension guidelines

References