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 Ξ²-blocker + Ξ±-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 Ξ±₂-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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