What is the recommended treatment for hypertension in pregnant women?

Management of Hypertension in Pregnancy

Dihydropyridine calcium channel blockers (preferably extended-release nifedipine), labetalol, and methyldopa are the recommended first-line medications for treating hypertension during pregnancy. 1

Diagnostic Classification of Hypertension in Pregnancy

• Hypertension in pregnancy is classified into several categories:
  • Chronic hypertension: Pre-existing hypertension before pregnancy or diagnosed before 20 weeks gestation 1
  • Gestational hypertension: New-onset hypertension after 20 weeks gestation without proteinuria 1
  • Pre-eclampsia: Gestational hypertension with proteinuria (≥0.3 g/day) or other maternal organ dysfunction 1
  • Pre-existing hypertension with superimposed gestational hypertension with proteinuria 1

Treatment Thresholds and Targets

• Drug treatment should be initiated in pregnant women with:

  • Confirmed office systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg 1
  • Target BP should be below 140/90 mmHg but not below 80 mmHg for diastolic BP 1

• For women with Stage 1 hypertension without target organ damage, some experts recommend initial non-pharmacological management with close monitoring 1

  • However, the most recent guidelines (2024) recommend pharmacological treatment at BP ≥140/90 mmHg 1

First-line Pharmacological Treatment Options

• Methyldopa: Traditional first-line agent with established safety record and long-term follow-up data on children 2

  • Dosage: Start with 250 mg 2-3 times daily, may increase gradually to maximum of 3g/day 2

• Labetalol: Alpha/beta-blocker with efficacy comparable to methyldopa 1

  • Can be administered orally or intravenously for severe hypertension 1

• Extended-release nifedipine: Dihydropyridine calcium channel blocker recommended as first-line option 1

  • Caution when using with magnesium sulfate due to risk of precipitous BP drop 1

Medications to Avoid During Pregnancy

• Renin-angiotensin system (RAS) blockers are strictly contraindicated during pregnancy 1

  • ACE inhibitors and ARBs cause severe fetotoxicity, particularly in second and third trimesters 1
  • Should be discontinued prior to conception or as soon as pregnancy is confirmed 1

• Atenolol should be used with caution due to association with fetal growth restriction 1

• Diuretics are generally avoided due to potential reduction in plasma volume, which is already compromised in pre-eclampsia 3

Management of Severe Hypertension/Hypertensive Emergency

• Severe hypertension (SBP ≥160 mmHg or DBP ≥110 mmHg) requires hospitalization and urgent treatment 1

• Intravenous options for hypertensive emergency include:

  • Labetalol: 20 mg IV bolus, then 40 mg after 10 minutes, followed by 80 mg every 10 minutes to maximum 220 mg 1
  • Hydralazine: 5 mg IV bolus, then 10 mg every 20-30 minutes to maximum 25 mg 1
  • Nifedipine: 10 mg orally, repeat every 20 minutes to maximum 30 mg 1

• Sodium nitroprusside should only be used when other treatments fail due to risk of fetal cyanide poisoning with prolonged administration 1

Non-pharmacological Management

• Low to moderate-intensity exercise is recommended for all pregnant women without contraindications to reduce risk of gestational hypertension and pre-eclampsia 1

• Normal diet without salt restriction is generally advised 1

  • However, some experts recommend limiting sodium to 2.4 g/day as in non-pregnant hypertensive patients 1

• Weight reduction is not recommended during pregnancy, even in obese women 1

  • However, achieving a healthy weight before pregnancy is beneficial 3

• Calcium supplementation (≥1 g daily) may be beneficial, particularly in high-risk women 1

• Low-dose aspirin is recommended for women with history of early-onset (<28 weeks) pre-eclampsia 1

Special Considerations

• Pre-pregnancy assessment is important for women with chronic hypertension to:

  • Evaluate BP control and adjust medications if needed 1, 3
  • Screen for secondary causes of hypertension 1, 3
  • Discontinue contraindicated medications 1, 3

• Close monitoring is essential for all hypertensive pregnant women to detect early signs of pre-eclampsia 1

• For women with target organ damage or requiring multiple antihypertensive agents before pregnancy, medication should be continued as needed 1

Treatment Algorithm

1. Confirm hypertension with repeated measurements
2. If BP ≥140/90 mmHg, initiate pharmacological treatment
3. First-line options: methyldopa, labetalol, or extended-release nifedipine
4. Target BP <140/90 mmHg but not <80 mmHg diastolic
5. For severe hypertension (≥160/110 mmHg), hospitalize and treat urgently
6. Monitor closely for signs of pre-eclampsia throughout pregnancy
7. Adjust treatment as needed based on BP control and tolerability