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Chapter 185. Pregnancy-Induced Hypertension, Chronic Hypertension in Pregnancy, Preeclampsia, Eclampsia

Imre Rédai, MD, FRCA

  • Chronic hypertension:
    • Systolic blood pressure >140 mm Hg or diastolic blood pressure >90 mm Hg prior to pregnancy of before 20 weeks of gestation
    • Hypertension that persists beyond the 12th postpartum week
  • Gestational hypertension:
    • New-onset hypertension after midpregnancy without proteinuria that resolves within 12 weeks postpartum
  • Preeclampsia:
    • New-onset hypertension after 20 weeks gestation associated with >300 mg per day proteinuria
    • New-onset seizures in the setting of preeclampsia are defined as eclampsia
  • Preeclampsia superimposed on chronic hypertension

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Hemodynamic Characteristics of Hypertensive Disorders during Pregnancy1
HealthyEarly preeclampsiaLate preeclampsiaGestational or chronic hypertension
Cardiac output6.28.95.09.0
Systemic vascular resistance1,2101,0821,687922
Wedge pressure7.59137
Stroke volume8010458110
LVSWI48613364
Colloid oncotic pressure18171418

1No ranges are given; numbers are presented for comparison as representative values.

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Chronic Hypertension
  • Affects 3% of pregnant population
  • More common in
    • African Americans (up to 44%)
    • Older gravidas (>12% after the age of 35)
Frequently associated with obesity, diabetes mellitus
  • Maternal complications
    • Superimposed preeclampsia
      • 10–25% incidence of progression to preeclampsia
      • 2.7-fold increase in risk for severe preeclampsia
    • Placental abruption
  • Commonly used oral medications1
    • α-Methyldopa
    • Labetalol
      • Metoprolol SR is an alternative
    • Nifedipine SR
  • Less commonly used oral medications1
    • Hydrochlorothiazide
    • Hydralazine (oral)
  • Fetal complications
    • IUGR/low birth rate
    • Fetal demise
  • Contraindicated in pregnancy1
    • ACEIs, ARBs, direct renin inhibitors
    • Propranolol (atenolol)

1Pharmacological options for the treatment of gestational hypertension are the same as those for chronic hypertension.

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Preeclampsia
  • Estimated frequency in healthy nulliparous women is 2–7%
  • Majority of cases (75%): mild, near term or intrapartum onset, negligible increase in risk for adverse outcome
  • Frequency and severity is higher with history of
    • Multiple gestation
    • Chronic hypertension
    • Prior pregnancy with preeclampsia
    • Pregestational diabetes mellitus
    • Thrombophilia
  • Maternal complications
    • Placental abruption (1–4%)
    • Disseminated coagulopathy/HELLP syndrome (10–20%)
    • Pulmonary edema/aspiration (2–5%)
    • Acute renal failure (1–5%)
    • Eclampsia (1%)
    • Liver failure or hemorrhage (1%)
    • Stroke (rare)
    • Death (rare)
    • Long-term cardiovascular morbidity
  • Diagnosis and management is supported by adequate prenatal care
  • Main objective remains the safety of the mother
  • Expectant management for pre-34 weeks remains controversial
  • Multisystem disorder with poorly understood pathomechanism
    • Abnormal vascular response to placentation
    • Placental humoral factors (sFlt-1, sEng) cause endothelial dysfunction in mother
  • Unique to human pregnancy
  • Characterized by
    • Microvascular dysfunction
    • Increased SVR
    • Activation of inflammatory pathways
    • Enhanced coagulation
    • Increased platelet activation and aggregation
    • Endothelial barrier dysfunction
  • Preeclampsia is most likely the common manifestation of a number of diseases affecting pregnant women
  • Fetal effects
    • IUGR/low birth weight
    • Reduced amniotic fluid
    • Restricted placental oxygen exchange, fetal hypoxia and neurological injury
  • Preterm delivery
  • Antihypertensives
    • Little evidence for benefit in mild/moderate cases
    • Severe hypertension (>160 mm Hg systolic, >100 mm Hg diastolic) should be treated to prevent maternal end-organ damage
    • Hydralazine was associated with more maternal side effects ...

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