What medications are recommended for hypertension in pregnancy?

Recommended Antihypertensive Medications for Hypertension in Pregnancy

Labetalol, extended-release nifedipine, and methyldopa are the three first-line antihypertensive medications recommended for treating hypertension during pregnancy, with labetalol and nifedipine generally preferred over methyldopa due to methyldopa's association with postpartum depression. 1

First-Line Oral Agents for Non-Severe Hypertension

Labetalol

• Labetalol is a first-line agent with efficacy comparable to methyldopa and can be administered orally for non-severe hypertension or intravenously for severe hypertension 1
• Dosing ranges from 200-800 mg twice daily, though postpartum patients may require more frequent dosing due to accelerated drug metabolism 2
• The main contraindication is a 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

Extended-Release Nifedipine

• Extended-release nifedipine is recommended as a first-line calcium channel blocker with the long-acting formulation used for maintenance therapy 1
• Dosing is typically 30-60 mg once daily, offering the advantage of once-daily administration which improves adherence 3
• Nifedipine demonstrates superior efficacy in controlling persistent hypertension compared to hydralazine and labetalol in meta-analyses 5
• It is safe during breastfeeding and aligns with standard hypertension guidelines 2

Methyldopa

• Methyldopa has the longest safety record with long-term infant follow-up data (7.5 years) from trials conducted 30 years ago 6, 1
• However, methyldopa should be used with caution in women at risk of developing depression and switched to an alternative agent in the postpartum period 1, 2
• It is safe during breastfeeding with minimal infant exposure 7
• In low- and middle-income countries, methyldopa and nifedipine are more readily available and cost-effective than other agents 6

Blood Pressure Targets During Pregnancy

• Treatment should be initiated for confirmed systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg 1
• The target blood pressure during pregnancy should be 110-135/85 mmHg to reduce the risk of accelerated maternal hypertension while minimizing impairment of fetal growth 1, 3
• Diastolic blood pressure should not be lowered below 80 mmHg 6

Acute Management of Severe Hypertension

Blood pressure ≥160/110 mmHg sustained for more than 15 minutes constitutes a hypertensive emergency requiring treatment within 30-60 minutes. 2

First-Line Agents for Severe Hypertension

Intravenous labetalol, oral immediate-release nifedipine, or intravenous hydralazine are the preferred options for acute severe hypertension: 6, 1

• IV labetalol: Start with 20 mg IV bolus, followed by 40-80 mg every 10 minutes until desired effect or maximum cumulative dose of 300 mg 2
• Oral immediate-release nifedipine: 10-20 mg orally, can be repeated as needed 2
• IV hydralazine: 5 mg IV initially, then 5-10 mg IV every 30 minutes as needed, though it is no longer the drug of choice due to association with more perinatal adverse effects 2, 8

The goal is to reduce mean arterial pressure by 15-25%, targeting systolic BP 140-150 mmHg and diastolic BP 90-100 mmHg 2

Medications Strictly Contraindicated in Pregnancy

ACE inhibitors, angiotensin receptor blockers (ARBs), and direct renin inhibitors are absolutely contraindicated during pregnancy due to severe fetotoxicity, particularly in the second and third trimesters. 6, 1, 3

• If taken inadvertently during the first trimester, immediately switch to another medication and arrange close monitoring including fetal ultrasound 6
• Atenolol should also be avoided, especially in early pregnancy, due to concerns about fetal growth restriction 1, 2
• Diuretics are generally not recommended as first-line agents due to the risk of reducing uteroplacental perfusion 1, 3

Regional Considerations for Low-Resource Settings

In low- and middle-income countries where resources are limited:

• Methyldopa and nifedipine are more readily available and cost-effective compared to oxprenolol, diltiazem, and prazosin 6
• Task-shifting policies should allow lower-level providers to initiate antihypertensive treatment for asymptomatic women without proteinuria 6
• Community-based BP measurement and protein dipsticks should be available at the first point of care 6

Non-Pharmacological Management

• A normal diet without salt restriction is advised, particularly close to delivery, as salt restriction may induce low intravascular volume 6
• Calcium supplementation of at least 1g daily during pregnancy may reduce the risk of pre-eclampsia 6, 1
• Low-dose aspirin (75-100 mg/day) should be administered at bedtime in women with a history of early-onset (<28 weeks) pre-eclampsia, starting before 16 weeks gestation 6
• Low to moderate-intensity exercise is recommended for all pregnant women without contraindications 1

Postpartum Management

• Blood pressure should be recorded shortly after birth and again within 6 hours 6
• Close BP monitoring is essential for at least 3 days postpartum, as this is when BP peaks and the majority of hypertension-related maternal deaths occur 2
• Avoid NSAIDs for postpartum analgesia in women with preeclampsia, especially those with renal disease, as NSAIDs can worsen hypertension 2
• For maintenance therapy postpartum, nifedipine extended-release or amlodipine are preferred over labetalol due to once-daily dosing and potentially superior efficacy 2
• All women should have BP and urine checked at 6 weeks postpartum, with persistent hypertension confirmed by 24-hour ambulatory monitoring 2

Long-Term Cardiovascular Risk

Women with pregnancy-related hypertensive disorders are at significantly increased risk of developing chronic hypertension, stroke, ischemic heart disease, and thromboembolic disease later in life. 1, 2, 8

• Cardiovascular risk assessment and lifestyle modifications are recommended for all women with a pregnancy-related hypertensive disorder 2
• Obstetric history should become part of routine cardiovascular risk assessment in women 9