What is the management of hypertension in pregnancy?

Management of Hypertension in Pregnancy

First-line antihypertensive medications for pregnant women include methyldopa, labetalol, and dihydropyridine calcium channel blockers (particularly nifedipine), while ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated due to fetal toxicity. 1

Classification of Hypertension in Pregnancy

Hypertension in pregnancy is classified into four categories:

1. Pre-existing (chronic) hypertension: Present before pregnancy or diagnosed before 20 weeks gestation
2. Gestational hypertension: Develops after 20 weeks gestation without proteinuria
3. Pre-eclampsia: Gestational hypertension with proteinuria (≥0.3 g/day or ACR ≥30 mg/mmol) or other maternal organ dysfunction 1
4. Pre-existing hypertension with superimposed gestational hypertension with proteinuria 2

Blood Pressure Thresholds and Targets

• Treatment initiation threshold:

  • BP ≥140/90 mmHg in women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with organ damage or symptoms 1
  • BP ≥150/95 mmHg in other pregnant women according to 2013 ESH/ESC guidelines 1

• Target BP levels:

  • <140/90 mmHg but not below 80 mmHg for diastolic BP 1
  • For severe hypertension, decrease mean BP by 15-25% and aim for 140-150/90-100 mmHg 1

Pharmacological Management

First-line Medications:

1. Methyldopa:

   • Drug of choice in pregnancy 1
   • Dosage: 250-500 mg divided twice daily or more frequently 1, 3
   • Long-term follow-up studies show no adverse effects on children's development 3

2. Labetalol:

   • Efficacy comparable to methyldopa 2
   • Dosage: 200-800 mg divided twice daily or more frequently 1
   • Preferred first-line treatment for hypertensive emergencies (IV formulation) 1

3. Calcium Channel Blockers:

   • Nifedipine XR: 30-60 mg once daily 1
   • Amlodipine: 5-10 mg once daily 1, 4
   • Note: Short-acting oral nifedipine should be avoided except in low-resource settings 1

Contraindicated Medications:

• ACE inhibitors and ARBs: Absolutely contraindicated due to severe fetotoxicity, particularly in second and third trimesters 2, 1
• Direct renin inhibitors: Contraindicated 1
• Diuretics: Use with caution, not first-line agents 1
• Atenolol: Use with caution due to risk of intrauterine growth retardation 1

Management of Hypertensive Emergencies

• Definition: BP ≥160/110 mmHg in the setting of pre-eclampsia or eclampsia 1, 5
• Management:
  • IV labetalol is preferred first-line treatment 1
  • If IV access unavailable: oral labetalol (200 mg) or methyldopa (1.0-1.5 g) 1
  • Short-acting nifedipine (10-20 mg) only when other options unavailable 1

Non-pharmacological Management

• Mild hypertension (140-150/90-99 mmHg): Consider non-pharmacological management 2

  • Close supervision
  • Limitation of activities
  • Some bed rest in left lateral position
  • Normal diet without salt restriction (salt restriction may induce low intravascular volume) 2

• Preventive measures:

  • Calcium supplementation (at least 1g daily) may reduce risk of pre-eclampsia 2
  • Low-dose aspirin (75-100 mg/day) prophylactically for women with history of early-onset (<28 weeks) pre-eclampsia, starting before 16 weeks gestation 2, 1

Postpartum Management

• Close monitoring: For 24-72 hours postpartum as hypertension may worsen between days 3-6 1
• Follow-up: Review within 1 week if still requiring antihypertensives at hospital discharge 1
• Weight management: Women should aim to achieve pre-pregnancy weight by 12 months postpartum 1

Long-term Considerations

• Women with history of preeclampsia have nearly four times higher risk of developing arterial hypertension later in life 1
• Regular monitoring of blood pressure, fasting lipids, and blood glucose is necessary 1
• The risk of developing ischemic heart disease is more than doubled in women with history of hypertensive disorders in pregnancy 1

Multidisciplinary Approach

A team approach including cardiologists, obstetricians, anesthesiologists, neonatologists, and geneticists is recommended for women with heart disease during pregnancy 1.

Common Pitfalls to Avoid

• Failing to distinguish between different types of hypertension in pregnancy
• Using ACE inhibitors or ARBs during pregnancy
• Using short-acting nifedipine which can cause uncontrolled hypotension
• Excessive BP reduction which may compromise uteroplacental perfusion
• Neglecting postpartum monitoring when risk of complications remains high