What is the initial management of hypertension in a pregnant patient?

Hypertension Workup in Pregnancy

Initial Assessment and Classification

Begin by measuring blood pressure accurately and classifying the hypertensive disorder, as the type determines both workup intensity and management urgency. 1

Blood Pressure Measurement

• Measure BP in a monitored setting using proper technique (seated, 5 minutes rest) 1
• Confirm elevated readings with repeat measurements before initiating treatment 1
• Consider home BP monitoring as a useful adjunct, particularly for chronic hypertension and white-coat hypertension 1

Classification of Hypertensive Disorders

Determine which category applies:

• Chronic hypertension: Hypertension present before 20 weeks gestation (complicates 1-5% of pregnancies) 2
• Gestational hypertension: New-onset hypertension after 20 weeks without proteinuria 2
• Preeclampsia: Gestational hypertension with proteinuria ≥30 mg/mmol on spot urine protein/creatinine ratio 1, 2
• Superimposed preeclampsia: Pre-existing hypertension that worsens with new proteinuria after 20 weeks 2

Essential Workup Components

Proteinuria Assessment

• Screen with automated dipstick urinalysis first 1
• If positive, quantify with spot urine protein/creatinine ratio (abnormal if ≥30 mg/mmol or 0.3 mg/mg) 1
• This distinguishes gestational hypertension from preeclampsia, which fundamentally changes management 1

Laboratory Evaluation

For all pregnant women with hypertension, obtain:

• Hemoglobin and platelet count (minimum twice weekly in preeclampsia to detect thrombocytopenia) 1
• Liver function tests (AST, ALT) to identify HELLP syndrome features 1
• Renal function tests (creatinine, BUN) and uric acid (elevated uric acid associated with worse maternal/fetal outcomes) 1
• Electrolytes if considering diuretic therapy or severe disease 1

Clinical Assessment

• Evaluate for neurological symptoms: severe headache, visual scotomata, hyperreflexia with clonus 1
• Assess for right upper quadrant or epigastric pain (liver capsule distension) 2
• Check for pulmonary edema (auscultation, oxygen saturation) 1

Fetal Assessment

• Initial ultrasound to confirm fetal well-being and assess growth 1
• In preeclampsia with fetal growth restriction, implement serial surveillance schedule 1
• Doppler studies of uterine arteries if available, particularly in high-risk patients 1

Secondary Hypertension Screening

• In women under age 40 with chronic hypertension, screen for secondary causes 1
• Prioritize obstructive sleep apnea evaluation in obese young adults 1
• Consider renal artery stenosis, primary aldosteronism, pheochromocytoma, and thyroid disorders based on clinical suspicion 1

Risk Stratification

High-Risk Features Requiring Hospital Assessment

Women with preeclampsia should be assessed in hospital when first diagnosed 1. Admit immediately if:

• Severe hypertension (≥160/110 mmHg) 1
• Neurological symptoms (severe headache, visual changes, altered mental status) 1
• Laboratory abnormalities (platelets <100,000, elevated liver enzymes >2x normal, creatinine >1.1 mg/dL) 1
• Pulmonary edema or cyanosis 1
• Fetal compromise (non-reassuring fetal status, severe growth restriction) 1

Preeclampsia Risk Assessment

Identify women who would have benefited from aspirin prophylaxis (though this is retrospective at presentation):

• Prior preeclampsia 1
• Chronic hypertension 1
• Pregestational diabetes 1
• BMI >30 kg/m² 1
• Antiphospholipid syndrome 1
• Assisted reproduction 1

Treatment Thresholds Based on Workup Findings

Severe Hypertension (Emergency)

BP ≥160/110 mmHg requires urgent treatment in a monitored setting 1:

• First-line: Oral nifedipine (immediate-release) OR IV labetalol OR IV hydralazine 1
• Oral labetalol if IV access unavailable 1
• Goal: Reduce BP gradually to avoid compromising uteroplacental perfusion 1

Non-Severe Hypertension Treatment Thresholds

Treatment initiation depends on classification:

• Gestational hypertension or chronic hypertension: Treat if BP consistently ≥140/90 mmHg 1
• Preeclampsia: Treat at ≥140/90 mmHg (lower threshold due to higher risk) 1, 2
• Target diastolic BP of 85 mmHg (systolic 110-140 mmHg), but never below 80 mmHg diastolic to maintain uteroplacental perfusion 1

Safe Antihypertensive Medications

First-line agents (all pregnancy category B or C with extensive safety data):

• Methyldopa (longest safety record with 7.5-year infant follow-up) 1, 2
• Labetalol (beta-blocker with alpha-blocking properties) 1, 2
• Extended-release nifedipine (dihydropyridine calcium channel blocker) 1, 2

Second-line agents:

• Hydralazine 1
• Prazosin 1

Absolutely contraindicated:

• ACE inhibitors (fetotoxic - cause renal dysgenesis, oligohydramnios, IUGR) 1, 2
• Angiotensin receptor blockers (same fetal risks as ACE inhibitors) 1, 2
• Spironolactone (antiandrogenic effects) 1

Special Considerations

Magnesium Sulfate Prophylaxis

Administer MgSO₄ for seizure prophylaxis in preeclampsia with:

• Severe hypertension (≥160/110 mmHg) 1
• Neurological signs or symptoms (hyperreflexia, visual changes, severe headache) 1

Delivery Timing

Deliver at 37 weeks + 0 days in preeclampsia, or earlier if 1:

• Refractory severe hypertension despite 3 antihypertensive classes 1
• Progressive thrombocytopenia 1
• Worsening liver or renal function 1
• Pulmonary edema 1
• Severe neurological symptoms or eclampsia 1
• Non-reassuring fetal status 1

Outpatient vs. Inpatient Management

After initial hospital assessment, stable preeclampsia may be managed outpatient if 1:

• BP controlled on oral medications 1
• No severe features present 1
• Patient reliable for home BP monitoring and symptom reporting 1
• Close follow-up available (typically twice weekly) 1

Common Pitfalls to Avoid

• Do not aggressively lower BP below 80 mmHg diastolic - risks compromising uteroplacental perfusion and fetal growth 1
• Do not continue ACE inhibitors or ARBs even if BP well-controlled - switch immediately upon pregnancy recognition 1, 2
• Do not rely on single BP measurement - confirm with repeated measurements or home monitoring 1
• Do not miss proteinuria assessment - this distinguishes preeclampsia from gestational hypertension and changes management intensity 1
• Do not discharge preeclampsia patients without ensuring twice-weekly lab monitoring capability 1