Treatment of Hypertension in Pregnancy

Treatment of Hypertension in Pregnancy

Introduction

Hypertensive disorders of pregnancy are a major cause of maternal and fetal morbidity and mortality worldwide. Proper classification, timely blood pressure control, and use of pregnancy-safe antihypertensive drugs are essential to prevent complications such as stroke, placental abruption, and fetal growth restriction.

This article provides a clear, guideline-based approach to the treatment of hypertension in pregnancy, suitable for clinicians, trainees, and exam preparation.

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Types of Hypertension in Pregnancy

1. Chronic Hypertension

• Hypertension diagnosed before pregnancy or before 20 weeks of gestation

• May persist postpartum

• Higher risk of superimposed preeclampsia

2. Gestational Hypertension

• New-onset hypertension after 20 weeks

• No proteinuria or end-organ damage

• Can progress to preeclampsia

3. Preeclampsia / Eclampsia

• Hypertension after 20 weeks plus:

– Proteinuria

– Or organ dysfunction (renal, liver, CNS, hematologic)

• Eclampsia = preeclampsia with seizures

4. Superimposed Preeclampsia

• Chronic hypertension with new-onset proteinuria

• Or sudden worsening of BP / organ dysfunction

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Treatment Goals

• Prevent maternal complications (stroke, heart failure, placental abruption)

• Prevent fetal complications (growth restriction, prematurity, fetal death)

Blood Pressure Targets

• Urgent treatment required:

– SBP ≥160 mmHg

– DBP ≥110 mmHg

• Maintenance target:

– 140–150 / 90–100 mmHg

• Avoid excessive lowering:

– SBP <130 mmHg

– DBP <80 mmHg

(may reduce uteroplacental perfusion)

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Antihypertensive Drugs in Pregnancy

Labetalol

• Class: Combined β-blocker + α-blocker

• Dose (oral): 100–400 mg BID–TID

• IV use: Preferred agent for severe hypertension

• Advantages: Rapid onset, well tolerated, safe for fetus

• First-line drug in most guidelines

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Methyldopa

• Class: Central α₂-agonist

• Dose: 250–500 mg BID–TID

• Advantages: Longest safety record in pregnancy

• Limitations: Slow onset, sedation, fatigue, depression

• Suitable for chronic BP control, not emergencies

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Nifedipine (Extended Release)

• Class: Calcium channel blocker

• Dose: 30–60 mg once daily

• Advantages: Effective, oral, well tolerated

• Important: Avoid sublingual nifedipine (risk of sudden hypotension)

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Hydralazine

• Class: Direct arteriolar vasodilator

• Dose: IV 5–10 mg every 20–30 minutes

• Use: Acute severe hypertension

• Adverse effects: Reflex tachycardia, headache, flushing

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Drugs Contraindicated in Pregnancy

❌ ACE inhibitors

❌ Angiotensin receptor blockers (ARBs)

❌ Direct renin inhibitors

Reason:

• Fetal renal failure

• Oligohydramnios

• Skull hypoplasia

• Neonatal death

These drugs are teratogenic and must be avoided at all stages of pregnancy.

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Management of Severe Hypertension and Preeclampsia

Magnesium Sulfate

• Drug of choice for seizure prophylaxis

• Reduces risk of eclampsia

• Monitor reflexes, urine output, respiratory rate

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Delivery

• Definitive treatment for preeclampsia

• Indicated if:

– Gestational age ≥37 weeks

– Maternal instability

– Fetal compromise

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Monitoring

• Maternal:

– Blood pressure

– Liver function tests

– Platelet count

– Renal function

• Fetal:

– Growth assessment

– Amniotic fluid volume

– Doppler studies when indicated

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Key Take-Home Points

• Labetalol, methyldopa, and nifedipine are safe first-line drugs

• Treat BP ≥160/110 mmHg urgently

• Avoid over-aggressive BP lowering

• ACE inhibitors and ARBs are strictly contraindicated

• Magnesium sulfate prevents seizures in preeclampsia

• Delivery is the only definitive cure for preeclampsia

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