What is the management and treatment of pregnancy-induced hypertension (PIH)?

Management and Treatment of Pregnancy-Induced Hypertension

For pregnancy-induced hypertension (PIH), initiate antihypertensive medication when blood pressure persistently reaches ≥150/95 mmHg, or at ≥140/90 mmHg if pre-eclampsia, gestational hypertension with proteinuria, chronic kidney disease, or cardiac disease is present. 1

Blood Pressure Thresholds for Treatment

Non-Emergency Management

• Start pharmacologic treatment at BP ≥150/95 mmHg in all hypertensive pregnant women without additional risk factors 1
• Lower threshold of ≥140/90 mmHg applies when pre-eclampsia, gestational hypertension with proteinuria, chronic kidney disease, or cardiac disease is present 1
• Target diastolic BP of 85 mmHg (systolic <160 mmHg, some centers target 110-140 mmHg systolic) 1
• Reduce or cease antihypertensives if diastolic BP falls <80 mmHg 1

Hypertensive Emergency

• BP ≥160/110 mmHg requires immediate hospitalization and urgent treatment 1
• This constitutes a hypertensive emergency in pregnancy, particularly with pre-eclampsia/eclampsia 1

First-Line Antihypertensive Medications

For Non-Severe Hypertension (Outpatient)

Preferred agents: 1

• Methyldopa (oral)
• Labetalol (oral)
• Calcium channel blockers (nifedipine)

Second-line agents: 1

• Hydralazine
• Prazosin
• Oxprenolol

Avoid atenolol due to association with fetal growth retardation related to treatment duration 1

For Severe Hypertension/Emergency

First-line options: 1

• IV labetalol
• Oral methyldopa
• Oral nifedipine

Second-line: 1

• IV hydralazine (no longer first-line due to more perinatal adverse effects) 1

Special circumstances:

• Sodium nitroprusside IV for hypertensive crises (use <4 hours due to fetal cyanide/thiocyanate toxicity risk) 1
• Nitroglycerin IV for pre-eclampsia with pulmonary edema 1

Screening and Monitoring

Proteinuria Assessment

• Screen all hypertensive pregnant women for proteinuria in second half of pregnancy 1
• Significant proteinuria defined as >0.3 g/24h or albumin-to-creatinine ratio (ACR) ≥30 mg/mmol 1
• If dipstick ≥1+, obtain ACR in spot urine or 24-hour collection 1
• ACR <30 mg/mmol reliably excludes proteinuria 1

Biomarker Testing

• sFlt-1/PlGF ratio ≤38 excludes pre-eclampsia development in next week when clinically suspected 1

Maternal Monitoring in Pre-eclampsia

• BP monitoring 1
• Clinical assessment including clonus 1
• Blood tests twice weekly minimum: hemoglobin, platelet count, liver transaminases, creatinine, uric acid 1
• Repeat testing with any clinical status change 1

Fetal Monitoring

• Fetal biometry, amniotic fluid, umbilical artery Doppler at diagnosis 1
• Repeat every 2 weeks if initial assessment normal 1
• More frequent monitoring with fetal growth restriction 1

Non-Pharmacologic Management

Limited value in pregnancy, but consider: 1

• Close supervision and activity limitation for BP 140-149/90-95 mmHg 1
• Normal diet without salt restriction 1
• Continue regular exercise with caution 1
• Obese women should avoid weight gain >6.8 kg 1
• Do not attempt weight reduction during pregnancy (associated with reduced neonatal weight) 1

Prevention Strategies

Low-Dose Aspirin

• 100-150 mg daily from week 12 to weeks 36-37 for women at high or moderate risk of pre-eclampsia 1
• Prophylactic use in women with history of early-onset (<28 weeks) pre-eclampsia 1

Calcium Supplementation

• ≥1 g/day may reduce pre-eclampsia and preterm birth risk, particularly with low calcium diet 1
• General supplementation (2 g/day) not consistently beneficial 1

Not recommended: Fish oil supplementation 1

Delivery Timing

Gestational Hypertension Without Severe Features

• Deliver at ≥37 weeks gestation 1, 2
• Optimum timing 38-39 weeks based on retrospective data 1

Pre-eclampsia Without Severe Features

• Deliver at ≥37 weeks gestation 1

Severe Pre-eclampsia

Immediate delivery indications (regardless of gestational age): 1

• ≥34 weeks gestation 1
• Repeated severe hypertension despite 3 antihypertensive classes 1
• Progressive thrombocytopenia 1
• Progressively abnormal renal or liver tests 1
• Pulmonary edema 1
• Severe intractable headache, visual disturbances, or neurological features 1
• Eclampsia 1
• Non-reassuring fetal testing 1
• Suspected placental abruption 1

Expectant Management <34 Weeks

• May consider in select stable patients with severe pre-eclampsia between 24-32 weeks in tertiary centers 3
• Typically achieves 7-10 days prolongation 3
• At 24 weeks, high maternal morbidity with limited perinatal benefit 3

Seizure Prophylaxis and Management

Magnesium Sulfate

Indications: 1, 4

• All women with severe pre-eclampsia (proteinuria + severe hypertension, or hypertension + neurological symptoms) 4
• Eclampsia treatment 1, 4
• During labor and ≥24 hours postpartum in severe disease 5

Dosing: 1, 4

• Loading: 4 g IV over 5 min, then 1 g/h IV
• Alternative: 5 g IM each buttock, then 5 g IM every 4 hours
• Low-resource settings: 4 g IV or 10 g IM loading, then 5 g IM every 4 hours until delivery and 24 hours postpartum 1

Critical warning: 4

• Do not administer concomitantly with calcium channel blockers (risk of severe hypotension) 4

Corticosteroids for Fetal Lung Maturity

• Consider for all women with pre-eclampsia at ≤34 weeks gestation 1
• For gestational hypertension at ≤34 weeks only if delivery anticipated within 7 days 1
• Rescue dose may be considered at ≤34 weeks if ≥14 days after initial course and high risk of preterm delivery 1
• May consider for elective cesarean at ≤38 weeks to reduce respiratory morbidity 1

Postpartum Management

Blood Pressure Monitoring

• Check BP and urine at 6 weeks postpartum 1
• Confirm persistent hypertension with 24-hour ambulatory monitoring 1
• Refer women <40 years with persistent hypertension for secondary cause evaluation 1
• Refer if hypertension or proteinuria persists at 6 weeks 1

Antihypertensive Selection During Breastfeeding

Compatible agents: 1

• ACE inhibitors (benazepril, captopril, enalapril, quinapril)
• Calcium channel blockers (diltiazem, nifedipine, verapamil)
• Beta-blockers (labetalol, metoprolol, nadolol, oxprenolol, propranolol, timolol)
• Diuretics (furosemide, hydrochlorothiazide, spironolactone)
• Others (clonidine, hydralazine, minoxidil)

Caution with methyldopa in women at risk for depression 1

Critical Pitfalls to Avoid

• Do not use IV hydralazine as first-line (more perinatal adverse effects) 1
• Avoid prolonged sodium nitroprusside (>4 hours increases fetal cyanide poisoning risk) 1
• Do not use diuretics in pre-eclampsia (plasma volume already reduced) 1
• Do not rely on proteinuria changes to dictate severity or management 2
• Do not use edema for diagnosis (occurs in 60% of normal pregnancies) 1
• Avoid classifying as "mild" vs "severe" pre-eclampsia clinically—all cases may rapidly become emergencies 1