What are the management options for hypertension (high blood pressure) in pregnancy?

Management of High Blood Pressure in Pregnancy

Blood Pressure Thresholds and Treatment Initiation

Start antihypertensive medication at BP ≥140/90 mmHg in women with gestational hypertension (with or without proteinuria), pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms. 1, 2 For all other pregnant women with hypertension, initiate treatment at BP ≥150/95 mmHg. 1

• Severe hypertension (SBP ≥170 mmHg or DBP ≥110 mmHg) constitutes an emergency requiring immediate hospitalization and urgent treatment to prevent maternal stroke and eclampsia. 1, 2, 3
• Diagnosis requires at least two elevated BP measurements on separate occasions. 4

Target Blood Pressure

Maintain BP between 110-135/80-85 mmHg to reduce maternal risk while preserving uteroplacental perfusion. 4, 1, 2

• Never lower diastolic BP below 80 mmHg—aggressive BP reduction below this threshold directly correlates with increased small-for-gestational-age infants. 2
• Target systolic BP below 140 mmHg but maintain diastolic above 80 mmHg. 1, 2

First-Line Pharmacological Management

For Mild-Moderate Hypertension (140-159/90-109 mmHg)

Use methyldopa, labetalol, or extended-release nifedipine as first-line oral agents. 1, 2

• Methyldopa has the longest safety record with adequate infant follow-up (7.5 years) and is considered the drug of choice. 1, 5
• Labetalol is optimal when both hypertension and tachycardia are present, providing dual alpha- and beta-blocking effects. 2
• Extended-release nifedipine (dihydropyridine calcium channel blocker) is effective but may worsen tachycardia through reflex sympathetic activation. 1, 2

For Severe Hypertension (≥160/110 mmHg)

Administer IV labetalol, oral methyldopa, or oral nifedipine immediately upon hospitalization. 4, 1, 2

• IV labetalol dosing: 100 mg twice daily up to 2400 mg/day. 4
• Target BP reduction to 140-150/90-100 mmHg. 3
• Do not use IV hydralazine as first-line therapy—it is associated with greater perinatal adverse effects compared to labetalol. 4, 2

Absolutely Contraindicated Medications

ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated throughout pregnancy due to severe fetotoxicity including renal dysgenesis. 4, 1, 2, 5, 6

• If discovered in early pregnancy, switch immediately to safe alternatives and arrange close fetal ultrasound monitoring. 2
• Atenolol is contraindicated due to associations with intrauterine growth retardation. 2, 6

Critical Medications to Avoid in Acute Management

• Do not use sublingual or IV nifedipine—risk of excessive and rapid BP reduction. 4
• Avoid combining calcium channel blockers with IV magnesium sulfate—risk of excessive hypotension that could harm mother and fetus. 4, 7
• Do not prolong nitroprusside use—risk of fetal cyanide toxicity. 4
• Do not use short-acting nifedipine—not FDA-approved for hypertension and can cause precipitous BP drops. 2

Non-Pharmacological Management

For BP 140-150/90-99 mmHg without organ damage, consider initial non-pharmacological approach: 1

• Normal diet without salt restriction (particularly near delivery to maintain intravascular volume). 4, 1, 2
• Limitation of activities and bed rest in left lateral position may be beneficial. 4, 1
• Do not attempt weight reduction, even in obese pregnant women—can lead to reduced neonatal weight. 4, 2

Preeclampsia Prevention

Administer low-dose aspirin (75-100 mg/day) at bedtime starting before 16 weeks gestation in women with history of early-onset preeclampsia (<28 weeks). 1, 2

Monitoring Requirements

• Weekly BP monitoring until stable on antihypertensive regimen. 2
• Assess for preeclampsia symptoms at each visit: headache, visual disturbances, epigastric pain. 1
• Evaluate for proteinuria (≥300 mg/24h or ≥30 mg/mmol urinary creatinine in spot urine). 1
• Monitor for signs requiring delivery: fetal distress, intrauterine growth retardation, HELLP syndrome, pulmonary edema, visual disturbances. 2

Definitive Treatment

Delivery remains the only curative treatment for preeclampsia—medical treatment prevents complications but does not alter disease course. 4

Postpartum Management

• Continue antihypertensive medications postpartum with gradual tapering rather than abrupt cessation. 1
• Safe medications for breastfeeding: labetalol, nifedipine, methyldopa, enalapril, beta-blockers. 1
• Labetalol is excreted in minimal amounts in breast milk (approximately 0.004% of maternal dose). 8
• Nifedipine is excreted in human milk; nursing mothers are advised not to breastfeed when taking this drug. 7
• Monitor BP for 72 hours in hospital and 7-10 days postpartum. 2
• Review at 3 months postpartum to ensure BP, urinalysis, and laboratory abnormalities have normalized. 1

Long-Term Cardiovascular Risk

• Women with hypertensive disorders of pregnancy have 4-fold increased risk of future hypertension and 2-fold increased risk of ischemic heart disease. 2
• Annual cardiovascular risk assessment is required lifelong. 1, 2
• Aim to achieve pre-pregnancy weight by 12 months and adopt healthy lifestyle including regular exercise and healthy diet. 1