What is the initial medication and dose to start for a pregnant patient with hypertension (HTN)?

Initial Medication and Dosing for Hypertension in Pregnancy

For pregnant patients with hypertension, start with oral labetalol 100 mg twice daily, oral nifedipine (immediate-release) 10 mg, or methyldopa 250-500 mg three times daily as first-line agents, with labetalol and nifedipine preferred for their efficacy and tolerability. 1, 2, 3

Treatment Thresholds

Initiate antihypertensive therapy at BP ≥140/90 mmHg in women with:

• Gestational hypertension 1, 2
• Pre-existing hypertension with superimposed gestational hypertension 1, 2
• Hypertension with subclinical organ damage or symptoms 1, 2

For all other pregnant women with hypertension, initiate treatment at BP ≥150/95 mmHg. 1, 2

First-Line Medication Options and Dosing

Labetalol (Preferred)

• Starting dose: 100 mg orally twice daily 4
• Titration: Increase by 100 mg twice daily every 2-3 days based on standing BP 4
• Usual maintenance: 200-400 mg twice daily 4
• Maximum: 1,200-2,400 mg daily in divided doses 4
• Consider three times daily dosing if nausea or dizziness occurs 4
• Contraindicated in reactive airway disease 1
• May require TID or QID dosing due to accelerated metabolism in pregnancy 1

Nifedipine (Immediate-Release, Preferred)

• Starting dose: 10 mg orally 3, 5
• Can repeat hourly with dose escalation if needed 3
• Achieved blood pressure control in 84% of women in high-quality trials 3
• Superior efficacy compared to methyldopa (84% vs 76% achieving target BP, p=0.03) 3
• Extended-release formulations should NOT be used for acute management 1

Methyldopa (Alternative First-Line)

• Starting dose: 250-500 mg orally three times daily 2
• Dose range: 750 mg to 4 g per day in 3-4 divided doses 2
• Only medication with long-term safety data on infant outcomes 1, 2
• Less effective than nifedipine for acute control 3
• Major caveat: Avoid postpartum due to risk of postnatal depression 1, 2
• More poorly tolerated due to side effects (peripheral edema, dry mouth, drowsiness, mood effects) 1

Severe Hypertension Management (Emergency)

SBP ≥170 mmHg or DBP ≥110 mmHg requires immediate hospitalization and treatment within 30-60 minutes. 1, 2

Acute Treatment Options:

• Oral nifedipine 10-20 mg (immediate-release) 1, 2
• IV labetalol 20,40, or 80 mg 1
• Oral labetalol 200 mg 1
• Oral methyldopa 1000 mg (single dose) 3

IV hydralazine is NO LONGER the drug of choice due to association with more perinatal adverse effects compared to other agents 1, 2

Critical Timing Requirements

• Confirm persistent severe hypertension within 15 minutes 1
• Initiate treatment within 60 minutes of the FIRST severe BP measurement (not the second confirmation) 1
• Treatment should occur as rapidly as possible to prevent maternal stroke and other complications 1

Medications to AVOID

Absolutely contraindicated in pregnancy:

• ACE inhibitors (risk of fetal damage) 1
• Angiotensin receptor blockers (ARBs) 1
• Direct renin inhibitors 1
• Mineralocorticoid receptor antagonists 1
• Atenolol (risk of fetal growth restriction) 1, 2

Comparative Efficacy Data

A 2019 randomized controlled trial of 894 women demonstrated:

• Nifedipine: 84% achieved BP control 3
• Labetalol: 77% achieved BP control 3
• Methyldopa: 76% achieved BP control 3
• Nifedipine was significantly superior to methyldopa (p=0.03) 3
• All three drugs had similar safety profiles with <1% serious adverse events 3

Postpartum Considerations

Switch from methyldopa postpartum due to risk of postnatal depression 1, 2

Preferred postpartum agents:

• Nifedipine or amlodipine (once-daily dosing advantage) 1
• Enalapril (once-daily, safe with breastfeeding) 1
• Labetalol (though may be less effective postpartum and requires multiple daily doses) 1

Long-Term Implications

Women with gestational hypertension have:

• 4-fold increased risk of developing chronic hypertension 1
• 2-fold increased risk of ischemic heart disease 1
• Increased risk of stroke in later life 1
• Require long-term cardiovascular risk factor monitoring and lifestyle modifications 1