What medications are safe for hypertension (high blood pressure) during pregnancy?

Safe Blood Pressure Medications During Pregnancy

The three first-line safe medications for hypertension during pregnancy are labetalol, extended-release nifedipine, and methyldopa, as recommended by the American College of Obstetricians and Gynecologists. 1

First-Line Safe Medications

Labetalol

• Labetalol is a preferred first-line agent with efficacy comparable to methyldopa, and can be given orally for non-severe hypertension or intravenously for severe hypertension 1
• Maximum daily dose is 2400 mg per day in divided doses, typically starting at 100 mg twice daily and titrating upward as needed 2
• Main contraindication is history of reactive airway disease (asthma) 3
• Small amounts (approximately 0.004% of maternal dose) are excreted in breast milk, making it safe for breastfeeding 4
• May cause potential neonatal bradycardia and risk of small for gestational age infants 2

Extended-Release Nifedipine

• Extended-release nifedipine is consistently recommended as a first-line calcium channel blocker with established safety data in pregnancy 1, 3, 2
• Use only the long-acting formulation for maintenance therapy during pregnancy; short-acting formulation is reserved exclusively for rapid treatment of severe hypertension 1, 3, 2
• Maximum daily dose is 120 mg for maintenance therapy 2
• Offers the advantage of once-daily dosing, which improves patient adherence 3, 2
• Never use sublingual nifedipine due to risk of uncontrolled hypotension and maternal myocardial infarction 2
• Do not give nifedipine concomitantly with magnesium sulfate due to risk of precipitous hypotension and potential fetal compromise 2

Methyldopa

• Methyldopa has the longest safety record with long-term infant follow-up data, making it historically the gold standard 1, 3
• Should be used with caution in women at risk of developing depression 1, 3
• Must be switched to an alternative agent in the postpartum period due to its side effect profile, particularly depression risk 2
• Common side effects include lack of energy and dizziness, with 14.5% of women requiring transfer to another drug due to minor side effects 5

Blood Pressure Targets During Pregnancy

• Target blood pressure should be 110-135/85 mmHg to reduce the risk of accelerated maternal hypertension while minimizing impairment of fetal growth 1, 3
• Initiate treatment for confirmed office systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg 1
• Do not lower diastolic blood pressure below 80 mmHg to avoid compromising uteroplacental perfusion 1, 2

Medications That Are ABSOLUTELY CONTRAINDICATED

ACE Inhibitors, ARBs, and Direct Renin Inhibitors

• These medications are strictly contraindicated throughout pregnancy due to severe fetotoxicity, including renal dysgenesis, oligohydramnios, and fetal teratogenicity 1, 3, 2
• Must be discontinued prior to conception or as soon as pregnancy is confirmed 3, 2

Atenolol

• Should be avoided, especially in early pregnancy, due to concerns about fetal safety 1

Diuretics

• Generally not recommended as first-line agents due to risk of reducing uteroplacental perfusion 1, 3
• May reduce milk production in breastfeeding women 2

Treatment Algorithm for Severe Hypertension (≥160/110 mmHg)

For acute severe hypertension requiring immediate treatment within 60 minutes: 1, 2

1. First-line options:

   • IV labetalol 1
   • Oral immediate-release nifedipine (10-20 mg, repeatable after 30 minutes) 2
   • IV hydralazine 1

2. Second-line if first-line fails:

   • Switch to alternative first-line agent 2

Comparative Efficacy

• Nifedipine was estimated to have lower risk of persistent hypertension compared to hydralazine (RR 0.40) and labetalol (RR 0.71) in meta-analysis 6
• Beta blockers (labetalol) and calcium channel blockers (nifedipine) appear superior to methyldopa in preventing preeclampsia 2
• Treatment with methyldopa or nifedipine decreases maternal morbidity (severe hypertension, preeclampsia, renal impairment, placental abruption) and fetal morbidity (prematurity, NICU admission) compared to no medication 7

Important Clinical Considerations

• Blood pressure may worsen after delivery, particularly between days 3-6 postpartum or within the first 1-2 weeks, requiring home blood pressure monitoring 1, 2
• Preeclampsia may worsen or appear for the first time after delivery 1, 2
• Women with hypertension during pregnancy have increased risk of developing cardiovascular disease later in life and require appropriate long-term follow-up 1, 3
• Pregnant women with severe hypertension should be referred to hospital for management 1

Postpartum and Breastfeeding

Safe medications for breastfeeding mothers include: 2

• Nifedipine (extended-release)
• Labetalol
• Metoprolol
• Enalapril (unless neonate is premature or has renal failure)

Switch methyldopa to an alternative agent postpartum due to depression risk 2