What are the recommended antihypertensive medications for pregnant women with hypertension?

From the Guidelines

Labetalol, methyldopa, and nifedipine are the preferred medications for treating hypertension during pregnancy, as they have established safety records and effectively control blood pressure without harming the developing fetus. According to the most recent and highest quality study 1, labetalol and oral nifedipine are suggested as first-line treatment for hypertensive emergencies during pregnancy. The recommended dosages are typically labetalol 100-200 mg twice daily, methyldopa 250-500 mg two to three times daily, and extended-release nifedipine 30-60 mg daily.

Key Considerations

• ACE inhibitors, ARBs, and direct renin inhibitors should be strictly avoided due to the risk of fetal kidney damage and other birth defects 1.
• The goal of treatment is to maintain blood pressure below 150/100 mmHg while avoiding hypotension, which could reduce placental perfusion.
• Regular monitoring of blood pressure, kidney function, and fetal growth is essential throughout pregnancy.
• Treatment should be initiated promptly, as uncontrolled hypertension during pregnancy increases the risk of complications like preeclampsia, placental abruption, preterm birth, and growth restriction.

Additional Guidance

• Methyldopa should not be used primarily for urgent BP reduction, as stated in the 2020 European Heart Journal study 1.
• Magnesium sulfate is recommended for the prevention of eclampsia and treatment of seizures, but should not be given concomitantly with calcium channel blockers due to the risk of hypotension.
• Early maternal warning signs, such as SBP > 160 mmHg, tachycardia, and oliguria, should be followed by proper diagnostic workup and possibly treatment.

From the FDA Drug Label

Pregnancy Teratogenic Effects. Reproduction studies performed with methyldopa at oral doses up to 1000 mg/kg in mice, 200 mg/kg in rabbits and 100 mg/kg in rats revealed no evidence of harm to the fetus. Published reports of the use of methyldopa during all trimesters indicate that if this drug is used during pregnancy the possibility of fetal harm appears remote. In five studies, three of which were controlled, involving 332 pregnant hypertensive women, treatment with methyldopa was associated with an improved fetal outcome

Methyldopa is considered a suitable option for managing hypertension in pregnancy, as it has been shown to have a low risk of fetal harm and may even improve fetal outcomes 2.

• Key benefits:
  • Low risk of fetal harm
  • Improved fetal outcomes in some studies
• Important considerations:
  • Use only if clearly needed
  • Monitor for potential side effects

Pregnancy:Teratogenic Effects: Pregnancy Category C: Teratogenic studies were performed with labetalol in rats and rabbits at oral doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively. No reproducible evidence of fetal malformations was observed.

Labetalol may also be used in pregnancy, but the potential benefits must justify the potential risks to the fetus 3.

• Key considerations:
  • Use only if potential benefits outweigh potential risks
  • Monitor for potential side effects, such as hypotension, bradycardia, and hypoglycemia in infants.

From the Research

Hypertension Medications for Pregnancy

The following medications are commonly used to treat hypertension in pregnancy:

• Labetalol: used in 74.9% of patients with hypertensive disorders of pregnancy 4
• Nifedipine: used in 29.6% of patients with hypertensive disorders of pregnancy 4, and found to be effective in reducing blood pressure in pregnant women 5, 6
• Methyldopa: used in 4.4% of patients with hypertensive disorders of pregnancy 4, and recommended as a first-line treatment for nonsevere hypertension in pregnancy 7
• Hydralazine: used in 20.5% of patients with hypertensive disorders of pregnancy 4

Effectiveness of Medications

Studies have shown that:

• Nifedipine is effective in reducing blood pressure in pregnant women, with a success rate of 84% 5
• Labetalol and methyldopa are also effective, but with lower success rates of 77% and 76% respectively 5
• Oral nifedipine, labetalol, and methyldopa are suitable options for treating severe hypertension in pregnancy 6

Safety of Medications

The safety of these medications in pregnancy has been evaluated, with:

• Nifedipine found to have a low risk of adverse effects, with less than 2% of women experiencing hypotension 6
• Labetalol and methyldopa also found to be safe, with no significant differences in adverse maternal or fetal outcomes compared to other medications 5, 6