What are the diagnostic criteria for elevated and severe postpartum hypertension in postpartum women?

Diagnostic Criteria for Postpartum Hypertension

Postpartum hypertension is diagnosed when systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg on two separate occasions at least 4 hours apart (or 15 minutes apart for confirmation), while severe postpartum hypertension is defined as systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg. 1, 2, 3

Standard Hypertension Thresholds

The diagnostic criteria are consistent across major guidelines for the postpartum period:

• Elevated/Hypertensive BP: Systolic ≥140 mmHg OR diastolic ≥90 mmHg, confirmed on at least two occasions 1, 2, 3
• Timing of confirmation: Measurements should be at least 15 minutes apart for acute assessment, or at least 4 hours apart for non-urgent diagnosis 1, 2, 3
• Measurement location: These thresholds apply to clinic measurements; home BP monitoring uses slightly lower thresholds of ≥135/85 mmHg 4

Severe Hypertension Criteria

Severe postpartum hypertension requires immediate intervention and is defined as:

• Systolic BP ≥160 mmHg OR diastolic BP ≥110 mmHg 1, 5, 2, 3
• Persistence threshold: When severe BP persists for more than 15 minutes, this constitutes a hypertensive emergency requiring treatment within 30-60 minutes 1, 5, 2, 3
• Confirmation: A second severe BP measurement should ideally be obtained within 15 minutes, but treatment timing must be based on the first severe measurement, not delayed waiting for confirmation 1

Critical Timing for Severe Hypertension Management

The quality metric for severe hypertension management specifies that treatment must be initiated within 60 minutes of the first severe BP measurement (≥160/110 mmHg), not the confirmatory measurement 1. This is crucial because:

• Waiting for a second measurement can inappropriately delay treatment 1
• The risk of stroke and end-organ damage increases with each minute of untreated severe hypertension 5, 2
• If the episode resolves spontaneously (BP drops below severe range) within 60 minutes without treatment, this is acceptable 1

Persistent Severe Hypertension Episode Definition

A persistent severe hypertension episode is defined as a severe BP reading where either: 1

• BP is not documented to have decreased below severe range within 15 minutes, OR
• One or more repeat severe BP measurements occur at 15-60 minutes after episode onset (even if interspersed with non-severe readings), OR
• Both of the above 1

Critical Postpartum Monitoring Period

The highest risk period for hypertension-related maternal mortality is the first 1-6 days postpartum, when BP typically peaks 1, 2. During this window:

• Close BP monitoring is essential for at least 3 days postpartum 2
• BP should be checked at least 4-6 times daily if still hospitalized 2
• Most hypertension-related maternal deaths, including from stroke and cardiomyopathy, occur during this period 2

Time Course and Resolution

Understanding the natural history helps distinguish transient from persistent hypertension:

• Peak BP: Occurs in the first week postpartum, typically days 3-6 1
• Expected resolution: By postpartum weeks 2-4, BP typically stabilizes, though 40% may still have BP ≥140/90 mmHg at 16 days and 26% at 1 month 1
• Chronic hypertension threshold: BP that remains elevated beyond 12 weeks postpartum should prompt evaluation for chronic hypertension and secondary causes 1

Common Pitfalls to Avoid

Do not delay treatment of severe hypertension waiting for a confirmatory measurement - the 60-minute treatment window starts with the first severe BP reading 1. This is a critical safety issue, as delayed treatment significantly increases stroke risk 5, 2.

Do not discharge patients with preeclampsia without a clear BP monitoring plan for the critical first 3-7 days when BP peaks 2. Home BP monitoring with twice-daily measurements should be established before discharge 2.

Do not use the 2017 ACC/AHA lower thresholds (≥130/80 mmHg) for diagnosing hypertension in postpartum women - obstetric guidelines have not adopted these lower thresholds, and the standard remains ≥140/90 mmHg 1. While lower BP may identify higher-risk patients, this is not yet the diagnostic standard 1.