What is considered gestational hypertension?

Gestational Hypertension: Definition and Diagnostic Criteria

Gestational hypertension is defined as new-onset hypertension (blood pressure ≥140/90 mmHg) that develops after 20 weeks of gestation in a previously normotensive woman, without proteinuria, and typically resolves within 42 days postpartum. 1

Diagnostic Criteria

Blood Pressure Thresholds

• Systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg 1
• Diagnosis should be based on at least two high blood pressure readings on two separate occasions 1
• Classification of severity:
  • Mild: 140-159/90-109 mmHg 1
  • Severe: ≥160/110 mmHg 1

Timing

• Hypertension must develop after 20 weeks of gestation 1
• In most cases, resolves within 42 days postpartum 1

Absence of Proteinuria

• Distinguished from preeclampsia by the absence of significant proteinuria 1
• If proteinuria develops (≥0.3 g/day in a 24h urine collection or ≥30 mg/mmol urinary creatinine in a spot sample), the condition is classified as preeclampsia 1

Distinguishing from Other Hypertensive Disorders

Differentiation from Pre-existing Hypertension

• Pre-existing (chronic) hypertension: Blood pressure ≥140/90 mmHg that either predates pregnancy or develops before 20 weeks of gestation 1
• Caution: Early pregnancy physiological BP decrease may mask pre-existing hypertension 1

Differentiation from Transient Gestational Hypertension

• Transient gestational hypertension: Elevated BP detected in clinic that normalizes with repeated measurements over several hours 1
• Associated with 40% risk of developing true gestational hypertension or preeclampsia later in pregnancy 1

Differentiation from Preeclampsia

• Preeclampsia: Gestational hypertension plus significant proteinuria or other systemic manifestations 1
• Systemic manifestations may include:
  • Thrombocytopenia
  • Renal insufficiency
  • Impaired liver function
  • Pulmonary edema
  • Cerebral or visual symptoms 2

Clinical Significance

• Complicates 6-7% of pregnancies 1, 3
• Associated with poor organ perfusion 1
• Increases risk of adverse maternal and fetal outcomes:
  • Maternal: Risk of abruptio placentae, cerebrovascular events, organ failure 3
  • Fetal: Risk of intrauterine growth restriction, prematurity, and intrauterine death 1, 3

Monitoring Considerations

• 24-hour ambulatory blood pressure monitoring may be superior to conventional measurements for predicting complications 1
• Women with new-onset blood pressures of 130-139/80-89 mmHg after 20 weeks gestation have significantly increased risk of developing hypertensive disorders of pregnancy (2.41 times higher risk) 4

Management Approach

• Non-pharmacological management for mild hypertension (140-149/90-99 mmHg) 1, 3
• Pharmacological treatment generally recommended when BP ≥150/95 mmHg 3
• Severe hypertension (≥160/110 mmHg) requires immediate hospitalization 5
• Preferred medications: methyldopa, labetalol, and calcium antagonists (particularly nifedipine) 5, 3
• ACE inhibitors and angiotensin II receptor blockers are contraindicated 1, 3

Remember that gestational hypertension requires careful monitoring as it may progress to preeclampsia, and women with a history of gestational hypertension are at increased risk for cardiovascular disease later in life 5.