Hypertensive Disorders of Pregnancy

A Comprehensive Clinical Approach

Based on ACOG/SMFM Guidelines

Created by Chukwuma I. Onyeije, MD, FACOG

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Overview: The Spectrum of Disease

Hypertensive disorders of pregnancy are not a single entity but a spectrum of related conditions with distinct pathophysiology and management strategies.

Chronic Hypertension

Elevated BP predating pregnancy or diagnosed before 20 weeks

Gestational Hypertension

New-onset HTN ≥20 weeks without proteinuria or severe features

Preeclampsia

HTN with proteinuria or severe features ≥20 weeks

Superimposed Preeclampsia

Preeclampsia developing in a woman with chronic HTN

Central Management Principle: Anticipating disease trajectory and balancing maternal safety with fetal maturity
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Epidemiology

Incidence

Trends and Disparities

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Pathophysiology: Conceptual Framework

Chronic Hypertension

Represents pre-existing vascular disease with:

Gestational Hypertension

May represent:

Evidence Note: 15-45% of gestational hypertension evolves into preeclampsia, particularly when diagnosed before 32 weeks
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Pathophysiology: Preeclampsia

The Two-Stage Model

Stage 1: Abnormal Placentation (Asymptomatic)

Stage 2: Maternal Syndrome (Clinical Manifestations)

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Risk Factors for Preeclampsia

High-Risk Factors (RR 2-4)

  • History of preeclampsia (especially if severe or early)
  • Multifetal gestation
  • Chronic hypertension
  • Pregestational diabetes (Type 1 or 2)
  • Renal disease
  • Autoimmune disease (SLE, antiphospholipid syndrome)

Moderate-Risk Factors (RR 1.5-2)

  • Nulliparity
  • Maternal age ≥35 years
  • Obesity (BMI ≥30)
  • Family history of preeclampsia
  • Low socioeconomic status
  • Black race
  • Previous adverse pregnancy outcome (SGA, abruption, fetal loss)
  • Interval >10 years since previous pregnancy
ACOG Recommendation: Women with ≥1 high-risk factor or ≥2 moderate-risk factors should receive low-dose aspirin (81-162 mg daily) starting between 12-28 weeks (ideally before 16 weeks) and continuing until delivery Strong Evidence
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Screening and Diagnosis

Universal Screening

Diagnostic Criteria for Hypertension

Hypertension: SBP ≥140 mmHg or DBP ≥90 mmHg on two occasions at least 4 hours apart

Severe hypertension: SBP ≥160 mmHg or DBP ≥110 mmHg (can be confirmed within minutes to facilitate timely treatment)

Diagnostic Criteria for Preeclampsia

Hypertension (≥20 weeks) PLUS one of the following:

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Preeclampsia: Features of Severity

System Severe Features
Blood Pressure SBP ≥160 mmHg or DBP ≥110 mmHg on two occasions, minutes apart
Hematologic Platelets <100,000/μL
Hemolysis (elevated LDH, bilirubin, or low haptoglobin)
Hepatic Transaminases >2× upper limit
Severe RUQ or epigastric pain
Renal Creatinine >1.1 mg/dL or doubling from baseline
Oliguria <500 mL/24 hours (rarely used)
Pulmonary Pulmonary edema
Neurologic New-onset persistent headache unresponsive to medication
Visual disturbances (scotomata, photopsia, blindness)
Altered mental status, stroke
Uteroplacental Fetal growth restriction with abnormal Doppler studies
Important Note: Proteinuria severity does NOT define severity of preeclampsia. Severe proteinuria alone without other features does not warrant diagnosis of preeclampsia with severe features.
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Management Principles

Fundamental Concepts

Key Management Components

Surveillance

  • Blood pressure monitoring
  • Laboratory assessment
  • Symptom evaluation
  • Fetal monitoring

Intervention

  • Antihypertensive medication
  • Seizure prophylaxis (MgSO₄)
  • Corticosteroids for fetal maturity
  • Delivery timing
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Chronic Hypertension: Management

Initial Assessment

Pharmacologic Management

Treatment threshold (ACOG 2019): Persistent SBP ≥160 mmHg or DBP ≥110 mmHg Strong Evidence

Consider treatment: SBP 140-159 or DBP 90-109 mmHg, especially with:
  • End-organ damage
  • Secondary hypertension
  • Diabetes or renal disease
Consensus

First-Line Agents

Avoid: ACE inhibitors, ARBs (teratogenic), atenolol (growth restriction), diuretics (reduce plasma volume)
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Management by Gestational Age: <34 Weeks

Preeclampsia WITHOUT Severe Features

Expectant Management Until 37 Weeks Strong Evidence
  • Outpatient management often appropriate
  • BP checks 2× weekly
  • Labs weekly (CBC, liver enzymes, creatinine)
  • Fetal surveillance: NST/BPP 1-2× weekly
  • Growth ultrasound every 3-4 weeks
  • Patient education on warning symptoms

Preeclampsia WITH Severe Features

Delivery ≥34 weeks Strong Evidence

<34 weeks: Consider expectant management ONLY IF:
  • Maternal and fetal conditions stable
  • Available resources for intensive monitoring
  • Hospitalization required
  • Continuous fetal monitoring initially
  • Magnesium sulfate administration
  • Corticosteroids for fetal lung maturity
  • Antihypertensive therapy for severe-range BP
  • Daily labs (CBC, liver enzymes, creatinine)
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Management by Gestational Age: ≥34 Weeks

Diagnosis Delivery Timing Evidence
Preeclampsia with severe features ≥34 weeks: Deliver
May proceed after maternal stabilization		 Strong
Preeclampsia without severe features ≥37 weeks: Deliver
34-37 weeks: Expectant management acceptable		 Strong
Gestational hypertension without severe features ≥37 weeks: Deliver (individualize 37-38 weeks)
<37 weeks: Expectant management		 Consensus
Chronic hypertension (uncomplicated) 38-39 weeks: Deliver
May continue to 40 weeks if well-controlled		 Consensus
Superimposed preeclampsia with severe features ≥34 weeks: Deliver Strong
ACOG 2020: Delivery at 37 weeks recommended for preeclampsia without severe features (reduces maternal morbidity without increasing neonatal complications)
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Acute Severe Hypertension Management

Definition: SBP ≥160 mmHg or DBP ≥110 mmHg on two occasions, minutes apart

Goal: Reduce BP within 30-60 minutes to prevent maternal cerebrovascular complications while maintaining uteroplacental perfusion

Target BP: 140-150/90-100 mmHg (avoid aggressive lowering)

First-Line Agents Strong Evidence

Medication Dosing Notes
Labetalol IV 20 mg initial, then 40 mg, 80 mg every 10 min
Max cumulative: 220 mg		 Preferred in most situations
Avoid in asthma, heart failure
Hydralazine IV 5-10 mg every 20 min
Max cumulative: 20 mg		 May cause reflex tachycardia
Monitor for fetal heart rate changes
Nifedipine PO 10-20 mg, repeat in 20 min if needed
Max initial: 50 mg		 Immediate-release formulation
Easy to administer
Safe with magnesium sulfate
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Magnesium Sulfate for Seizure Prophylaxis

Indications Strong Evidence

Dosing

Loading dose: 4-6 grams IV over 15-20 minutes

Maintenance: 2 grams/hour continuous infusion

Duration: Continue for 24 hours postpartum (or 24 hours after last seizure in eclampsia)

Monitoring and Toxicity

Magnesium sulfate reduces eclampsia risk by approximately 60% compared to no treatment (Magpie Trial)
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Maternal Risks and Complications

Acute Complications

  • Eclampsia (seizures)
    • Occurs in 1-2% of preeclampsia with severe features
  • Stroke
    • Hemorrhagic or ischemic
    • Risk increases significantly with SBP >160
  • HELLP syndrome
    • Hemolysis, Elevated Liver enzymes, Low Platelets
    • 10-20% of severe preeclampsia
  • Acute kidney injury
  • Pulmonary edema
  • Hepatic rupture (rare but catastrophic)
  • Placental abruption (2-4× increased risk)
  • DIC

Long-Term Maternal Health

  • Cardiovascular disease
    • 2-4× increased lifetime risk
    • Risk of HTN, MI, stroke, heart failure
  • Chronic kidney disease
    • Particularly with early-onset or severe disease
  • Metabolic syndrome and diabetes
    • 2× increased risk of Type 2 diabetes
  • Recurrence risk
    • 15-25% overall recurrence
    • 40% if early-onset (<28 weeks)
    • 13% if term disease
Long-term follow-up essential: Women with history of preeclampsia should be counseled about cardiovascular risk and receive appropriate screening
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Fetal and Neonatal Risks

Antenatal/Intrapartum Risks

Neonatal Complications

Key Point: Perinatal mortality is primarily driven by prematurity rather than hypertension itself, underscoring the importance of balancing delivery timing with fetal maturity
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Key Counseling Points: Prevention and Early Detection

Preconception and Early Pregnancy Counseling

Warning Signs - When to Seek Care Immediately

Teach patients to report:
  • Severe headache that doesn't resolve with acetaminophen
  • Visual changes (blurred vision, seeing spots, sensitivity to light)
  • Right upper quadrant or epigastric pain
  • Nausea/vomiting in late pregnancy
  • Sudden swelling of face or hands
  • Decreased fetal movement
  • Shortness of breath or difficulty breathing
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Key Counseling Points: Management Expectations

If Diagnosed with Preeclampsia

Future Pregnancy Counseling

Long-Term Health

History of preeclampsia increases lifetime cardiovascular risk. Recommend:
  • Primary care follow-up within 7-14 days postpartum and at 6 weeks
  • Blood pressure monitoring
  • Cardiovascular risk factor screening and management
  • Healthy lifestyle (diet, exercise, weight management)
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Areas of Controversy and Evolving Evidence

1. Treatment Threshold for Chronic Hypertension

CHAP Trial (2022): Demonstrated that treating mild chronic hypertension (target <140/90) reduced composite adverse outcomes compared to reserving treatment for severe hypertension, without increasing SGA births

Debate: Some advocate for lower treatment threshold (SBP ≥140 or DBP ≥90), while others maintain conservative approach reserving treatment for ≥160/110

Current ACOG: Treatment recommended for persistent ≥160/110; consider for 140-159/90-109 with additional risk factors Evolving

2. Role of Angiogenic Biomarkers

sFlt-1/PlGF ratio shows promise for:
  • Predicting short-term development of preeclampsia
  • Risk stratification in women with suspected disease
  • Guiding expectant management decisions
Current status: FDA-approved in US, used more widely in Europe, not yet incorporated into routine ACOG guidelines Evolving
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Controversies and Evolving Evidence (cont.)

3. Delivery Timing for Preeclampsia Without Severe Features

HYPITAT Trial: Supported delivery at 37 weeks

Debate: Some centers deliver at 37 weeks routinely, others individualize 37-38 weeks based on cervical favorability and patient preference

ACOG 2020: Recommends delivery at 37 weeks Strong Evidence

4. Expectant Management <34 Weeks with Severe Features

Highly selected cases only (tertiary centers with intensive monitoring capability)

Debate centers on:
  • Which specific severe features allow expectant management (severe BP alone vs. lab abnormalities)
  • Duration of expectant management feasible
  • Maternal vs. neonatal risk trade-offs at extreme prematurity (23-28 weeks)
Consensus: Individualized

5. Postpartum Hypertension Management

Unresolved questions:
  • Optimal timing of antihypertensive initiation postpartum
  • Target blood pressures in immediate postpartum period
  • Duration of treatment (when to discontinue medications)
  • Role of outpatient BP monitoring (telehealth, home monitoring)
Growing focus on postpartum care to reduce maternal morbidity and mortality Evolving
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Controversies and Evolving Evidence (cont.)

6. Mode of Delivery

Key points:
  • Preeclampsia alone is NOT an indication for cesarean delivery
  • Induction of labor is safe and appropriate
  • Cesarean delivery reserved for standard obstetric indications
Evolving area: Optimal timing of induction vs. awaiting spontaneous labor in mild disease at term

7. Aspirin Dose and Timing

Current recommendation: 81-162 mg daily starting 12-28 weeks (ideally <16 weeks)

Ongoing questions:
  • Is 162 mg superior to 81 mg? (Limited high-quality data)
  • Should high-risk women start earlier (<12 weeks)?
  • Bedtime vs. morning dosing?
  • Should treatment continue beyond 36 weeks?
ACOG accepts 81-162 mg range Strong Evidence for Aspirin; specific dose Consensus

8. Home Blood Pressure Monitoring

Increasing acceptance for select patients with gestational hypertension or mild preeclampsia

Requires: Patient education, validated devices, clear action thresholds, reliable communication

Evidence: Limited RCT data but growing observational support Evolving
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Summary: Principles of Management

Core Concepts

  • Hypertensive disorders represent a spectrum, not a single disease
  • Management requires continuous reassessment of disease trajectory
  • Delivery is the only cure for preeclampsia
  • Goal is to balance maternal safety with fetal maturity
  • Decision-making integrates gestational age, severity, and maternal/fetal status

Prevention

  • Risk assessment
  • Low-dose aspirin for high-risk patients
  • Optimize chronic conditions

Surveillance

  • Frequent BP monitoring
  • Laboratory reassessment
  • Symptom evaluation
  • Fetal monitoring

Acute Management

  • Treat severe hypertension urgently
  • MgSO₄ for seizure prophylaxis
  • Corticosteroids <34 weeks

Delivery Timing

  • ≥34 weeks: severe features
  • ≥37 weeks: without severe features
  • Individualize based on trajectory
Remember: The clinician's role is to interpret blood pressures within the broader context of placental health, maternal reserve, and fetal well-being—not simply react to numbers.
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Key Takeaways for Clinical Practice

1. Risk Stratification is Essential

Identify high-risk patients early and initiate aspirin prophylaxis between 12-28 weeks (ideally <16 weeks)

2. Severe Hypertension is an Emergency

SBP ≥160 or DBP ≥110 requires urgent treatment within 30-60 minutes to prevent maternal stroke

3. Proteinuria Does Not Define Severity

Severe features are defined by end-organ involvement, not degree of proteinuria

4. Disease Can Progress Rapidly

Especially in the antepartum and first 48-72 hours postpartum period. Maintain high vigilance

5. Delivery Timing Requires Nuanced Decision-Making

Balance gestational age, disease severity, trajectory, and maternal/fetal status. There is no "one size fits all"

6. Long-Term Follow-Up is Critical

Counsel patients about future cardiovascular risk and ensure appropriate screening and preventive care

Most Important: Effective management demands clinical judgment that integrates evidence, patient factors, and real-time disease evolution. Guidelines provide the framework, but each patient requires individualized care.
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Key References and Guidelines

Primary Guidelines

Landmark Trials

Additional Resources

Questions?

Thank you for your attention

Remember: Hypertensive disorders of pregnancy demand continuous reassessment, anticipation of progression, and timely decisions grounded in physiology, evidence, and clinical judgment.