What is the recommended antihypertensive therapy for pregnant women with hypertension?

Antihypertensive Therapy in Pregnancy

For pregnant women with hypertension, first-line antihypertensive medications should be dihydropyridine calcium channel blockers (preferably extended-release nifedipine), labetalol, or methyldopa. 1

Blood Pressure Thresholds and Targets

• When to initiate treatment:

  • Start antihypertensive therapy when confirmed office systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg 1
  • Severe hypertension (≥160/110 mmHg) requires immediate treatment within 30-60 minutes 1

• Target blood pressure:

  • Lower BP below 140/90 mmHg but not below 80 mmHg for diastolic BP 1
  • Some guidelines suggest a narrower target range of 110-135/85 mmHg to reduce risk of accelerated maternal hypertension while minimizing impairment of fetal growth 1

First-Line Medication Options

1. Dihydropyridine Calcium Channel Blockers

• Extended-release nifedipine: Preferred option due to once-daily dosing and effectiveness 1
• Dosing: 30-60 mg once daily

2. Labetalol

• Widely recommended first-line agent 1
• Dosing: 200-800 mg divided twice daily or more frequently 2
• Consider in women with tachycardia or increased sympathetic activity

3. Methyldopa

• Traditional first-line agent for pregnancy hypertension 1
• Dosing: Start with 250 mg 2-3 times daily, can increase to 500 mg 2-4 times daily
• Note: Should be switched to an alternative medication postpartum due to risk of postnatal depression 1, 3

Medications to Avoid During Pregnancy

• Renin-angiotensin system (RAS) blockers: ACE inhibitors and angiotensin receptor blockers are contraindicated due to fetotoxicity 1
• Direct renin inhibitors: Contraindicated 1
• Diuretics: Generally not recommended for blood pressure control in pregnancy but may be considered in late pregnancy if needed for volume control 1
• Atenolol: Should be avoided due to risk of fetal growth restriction 1

Management of Severe Hypertension

For severe hypertension (≥160/110 mmHg), immediate treatment is required with:

• IV labetalol (first-line in many guidelines) 1
• Oral nifedipine 1
• IV hydralazine 1

Special Considerations

Preeclampsia Prevention

• Women with strong clinical risk factors for preeclampsia (prior preeclampsia, chronic hypertension, pregestational diabetes, BMI >30 kg/m², antiphospholipid syndrome, assisted reproduction) should receive:
  • Low-dose aspirin (75-162 mg/day) before 16 weeks but definitely before 20 weeks gestation 1
  • Supplemental calcium (1.2-2.5 g/day) if intake likely to be low (<600 mg/day) 1

Non-Pharmacological Approaches

• Low- to moderate-intensity exercise is recommended to reduce risk of gestational hypertension and preeclampsia 1
• Lifestyle modifications including sodium restriction (<2,300 mg/day), increased consumption of fruits, vegetables, and low-fat dairy products 1

Postpartum Management

• Hypertension may worsen after delivery, particularly between days 3-6 1
• Continue antihypertensive agents after delivery 1
• Switch methyldopa to an alternative medication postpartum 1, 3
• Monitor BP for at least 72 hours in hospital and 7-10 days postpartum 1
• Long-term follow-up is recommended as these women have increased lifetime cardiovascular risk 1, 4

Common Pitfalls and Caveats

1. Delayed treatment: Failing to promptly treat severe hypertension (≥160/110 mmHg) increases risk of maternal stroke and other complications.

2. Excessive BP lowering: Overly aggressive BP reduction may compromise uteroplacental perfusion and fetal growth.

3. Continuing contraindicated medications: ACE inhibitors and ARBs must be discontinued immediately when pregnancy is confirmed.

4. Neglecting postpartum monitoring: Hypertension can worsen in the early postpartum period, with risk of eclamptic seizures.

5. Missing long-term follow-up: Women with hypertensive disorders of pregnancy require monitoring for future cardiovascular disease risk.

By following these evidence-based recommendations, clinicians can effectively manage hypertension during pregnancy while minimizing risks to both mother and fetus.