How should I manage a pregnant woman after 20 weeks gestation with new‑onset hypertension, proteinuria, and possible severe features (severe hypertension, thrombocytopenia, impaired renal function, elevated liver enzymes, pulmonary edema, or neurologic symptoms) regarding blood pressure control, seizure prophylaxis, fetal monitoring, and delivery timing?

Management of Preeclampsia After 20 Weeks Gestation

All women with preeclampsia after 20 weeks gestation require immediate hospital assessment, urgent blood pressure control if ≥160/110 mmHg, magnesium sulfate for seizure prophylaxis when severe features are present, and delivery at ≥37 weeks or immediately if maternal/fetal deterioration occurs regardless of gestational age. 1, 2

Immediate Blood Pressure Management

Severe Hypertension (≥160/110 mmHg)

• Treat within 30-60 minutes as a hypertensive emergency to prevent maternal stroke or cerebral hemorrhage 1, 2
• First-line IV agent: Labetalol 20 mg bolus, repeat 40 mg after 10 minutes, then 80 mg every 10 minutes up to cumulative 220 mg 1, 2, 3
• Alternative IV agents if labetalol contraindicated: hydralazine or nifedipine 1
• Target blood pressure: systolic 110-140 mmHg and diastolic 85 mmHg (minimum goal <160/105 mmHg) 1, 2

Non-Severe Hypertension (140-159/90-109 mmHg)

• Initiate oral antihypertensive therapy for persistent BP ≥140/90 mmHg 1
• Acceptable first-line oral agents: methyldopa, labetalol, nifedipine, or oxprenolol 1
• Target diastolic BP of 85 mmHg to reduce likelihood of severe hypertension and complications 1
• Reduce or cease antihypertensives if diastolic BP falls <80 mmHg to maintain uteroplacental perfusion 1, 2

Critical Medication Safety Points

• Avoid short-acting oral nifedipine especially with concurrent magnesium sulfate due to risk of uncontrolled hypotension and fetal compromise 2
• Avoid sodium nitroprusside except as last resort (>4 hours use causes fetal cyanide/thiocyanate toxicity) 1, 2
• ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated due to severe fetotoxicity 2

Seizure Prophylaxis with Magnesium Sulfate

Indications for Magnesium Sulfate

• All women with severe preeclampsia (severe hypertension with proteinuria or neurological signs/symptoms) 1
• Any woman with preeclampsia and neurological symptoms including headache, visual disturbances, or hyperreflexia 1, 2, 4
• Continue during labor and for 24 hours postpartum 4, 5, 6

Dosing Protocol

• Loading dose: 4-5 g IV over 5 minutes (diluted to 10-20% concentration) 2, 5
• Maintenance infusion: 1-2 g/hour continuous IV 2, 5
• Alternative regimen: 4 g IV loading dose, then 4-5 g IM into alternate buttocks every 4 hours 5
• Maximum daily dose: 30-40 g per 24 hours 5

Monitoring for Magnesium Toxicity

• Check deep tendon reflexes before each dose (loss of patellar reflex indicates toxicity) 2, 5
• Monitor respiratory rate (respiratory depression is a toxicity sign) 2
• Hourly urine output via Foley catheter: target ≥100 mL per 4 hours or >35 mL/hour 2, 5
• Therapeutic serum magnesium level: 6 mg/100 mL (4.8-8.4 mg/dL) 5
• Do not exceed 5-7 days continuous use (prolonged use causes fetal abnormalities) 5

Maternal Monitoring Protocol

Clinical Assessment

• Blood pressure monitoring: every 4 hours minimum, continuous monitoring if severe hypertension 1, 4
• Neurological assessment: check for clonus, severe headache, visual scotomata, confusion, or agitation 1, 2
• Respiratory monitoring: oxygen saturation on room air (maternal early warning if <95%) 2
• Fluid restriction: 60-80 mL/hour to reduce pulmonary edema risk 2

Laboratory Surveillance

• Baseline labs at diagnosis: complete blood count (hemoglobin, platelets), liver transaminases (AST/ALT), serum creatinine, uric acid 1, 2, 4
• Repeat frequency: at least twice weekly, more frequently with clinical deterioration 1, 2
• Watch for HELLP syndrome: hemolysis, elevated liver enzymes (AST/ALT), platelets <100,000/µL 1, 2

Signs Requiring Immediate Escalation

• Severe persistent headache unresponsive to analgesia 1, 2
• Visual disturbances (scotomata, blurred vision, photophobia) 1, 2
• Epigastric or right upper quadrant pain (suggests hepatic capsule distension or HELLP) 1, 2
• Dyspnea or chest pain (pulmonary edema) 1, 2
• Oliguria (<100 mL per 4 hours) 2

Fetal Monitoring

Initial Assessment at Diagnosis

• Ultrasound evaluation: fetal biometry, amniotic fluid volume, umbilical artery Doppler 1, 2
• Continuous fetal heart rate monitoring if severe features present 2

Ongoing Surveillance

• Repeat ultrasound every 2 weeks if initial assessment normal 1, 2
• More frequent monitoring (amniotic fluid and Doppler) if fetal growth restriction present 1
• Non-stress testing as per obstetric protocols for high-risk pregnancy 1

Delivery Timing: Gestational Age-Based Algorithm

≥37 Weeks Gestation

• Deliver immediately after maternal stabilization regardless of severity 1, 2, 4
• Vaginal delivery preferred unless obstetric contraindications exist 1, 2, 4

34-37 Weeks Gestation

• Expectant conservative management if maternal and fetal status stable 1, 2
• Deliver immediately if any deterioration occurs: 1, 2
  • Inability to control BP despite ≥3 antihypertensive classes
  • Progressive thrombocytopenia
  • Progressively abnormal liver or renal function tests
  • Pulmonary edema
  • Severe intractable headache, visual scotomata, or seizures
  • Non-reassuring fetal status

<34 Weeks Gestation

• Conservative expectant management at tertiary center with Maternal-Fetal Medicine expertise 1, 2
• Administer antenatal corticosteroids for fetal lung maturity (betamethasone or dexamethasone) 1, 2
• Deliver immediately if absolute indications present (same criteria as 34-37 weeks) 1, 2

Absolute Indications for Immediate Delivery (Any Gestational Age)

• Repeated episodes of severe hypertension despite 3 classes of antihypertensives at appropriate doses 1, 2
• Progressive thrombocytopenia 1, 2
• Progressively abnormal renal or liver enzyme tests 1, 2
• Pulmonary edema (treat with IV nitroglycerin 5-100 µg/min, avoid plasma expansion) 1, 2
• Abnormal neurological features: severe intractable headache, repeated visual scotomata, or convulsions (eclampsia) 1, 2
• Non-reassuring fetal status or placental abruption 1, 2
• Maternal pulse oximetry deterioration 2

Intrapartum and Postpartum Management

During Labor and Delivery

• Continue antihypertensive therapy to maintain BP <160/110 mmHg 1, 2
• Continue magnesium sulfate infusion throughout labor 2, 4
• Avoid ergot alkaloids for third stage of labor (use oxytocin instead) 1

Postpartum Care

• Continue magnesium sulfate for 24 hours postpartum 4, 5, 6
• Blood pressure monitoring: at least every 4 hours while awake for minimum 3 days (hypertension can worsen days 3-6 postpartum) 2
• Replace methyldopa with alternative antihypertensive if used during pregnancy (risk of postpartum depression) 1, 2
• Acceptable antihypertensives compatible with breastfeeding: captopril, enalapril, labetalol, nifedipine, propranolol 1
• Follow-up at 6 weeks postpartum: check BP and urine; persistent hypertension or proteinuria requires specialist referral 1

Common Pitfalls to Avoid

• Do not attempt to classify as "mild versus severe" preeclampsia clinically—all cases may become emergencies rapidly 1, 2
• Do not use serum uric acid or level of proteinuria as criteria for delivery 1, 2
• Do not reduce antihypertensives if diastolic BP falls <80 mmHg (preserves uteroplacental perfusion) 1, 2
• Do not delay delivery for completion of corticosteroid course if maternal or fetal deterioration occurs 7
• Do not use plasma volume expansion routinely (increases pulmonary edema risk) 1, 2