Hypertensive Disorders of Pregnancy

Background

• Hypertension is the most common medical condition complicating pregnancy.
• There are multiple possible risk factors, the strongest of which are: prior preeclampsia, preexisting hypertension or diabetes, chronic kidney disease, antiphospholipid antibody syndrome, and multifetal pregnancy. Other important risk factors include advanced maternal age and elevated prepregnancy body mass index (BMI).
• Hypertension is defined as a persistent systolic blood pressure ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg.
  • Severe hypertension is defined as systolic blood pressure ≥ 160 mm Hg or diastolic blood pressure ≥ 110 mm Hg, measured twice, at least 15 minutes apart.
  • Non-severe hypertension is defined as systolic blood pressure 140-159 mm Hg or diastolic blood pressure 90-109 mm Hg.
• Hypertensive disorders of pregnancy include both chronic hypertension diagnosed before pregnancy or prior to 20 weeks gestation, and new-onset hypertension developing after 20 weeks gestation in a current pregnancy.
  • Gestational hypertension is new-onset hypertension that develops at ≥ 20 weeks gestation, without evidence of preeclampsia.
  • Preeclampsia is hypertension with new onset proteinuria (> 300 mg/24 hours) after 20 weeks gestation, or, if no proteinuria, diagnosis requires ≥ 1 of severe features, which include:
    • thrombocytopenia (platelet count < 100 x 10⁹/L)
    • impaired liver function that is not accounted for by alternative diagnoses, indicated by either of the following
      • elevated serum liver transaminases to more than twice normal concentration
      • severe, persistent right upper quadrant or epigastric pain refractory to medication
    • new renal insufficiency (elevated serum creatinine > 1.1 mg/dL or doubling of serum creatinine in patient without other renal disease)
    • pulmonary edema
    • new onset headache refractory to medication and not accounted for by alternate diagnoses
    • visual disturbances
  • Preeclampsia with severe features is characterized by severe hypertension or non-severe hypertension in the presence of other severe complications, including, but not limited to those listed above.
  • Other types of hypertension in pregnancy include:
    • preeclampsia superimposed on chronic hypertension
    • eclampsia, defined as new-onset generalized seizures in woman with preeclampsia

Evaluation

• In women with known or suspected chronic hypertension:
  • Perform preconception or early pregnancy evaluation to rule out secondary (potentially curable) hypertension and identify possible end-organ involvement (Strong recommendation).
  • Obtain baseline testing for comparison if preeclampsia is suspected later in pregnancy (Strong recommendation), including:
    • blood tests to assess serum creatinine, electrolytes, liver enzymes, and platelet count
    • urinalysis (dipstick test or quantification of urine protein)
• In women with gestational hypertension or preeclampsia:
  • Initial evaluation includes
    • blood tests for assessment of (Strong recommendation):
      • complete blood count with platelet estimate
      • serum creatinine
      • liver enzymes
    • urinalysis for measurement of proteinuria (Strong recommendation)
      • Urinary dipstick testing is recommended for screening if suspicion of preeclampsia is low.
      • Definitive testing with urinary protein:creatinine ratio or 24-hour urine collection is recommended if urinary dipstick proteinuria is ≥ 1+ in women with either of the following (Strong recommendation):
        • hypertension and rising blood pressure
        • normal blood pressure, but symptoms or signs suggestive of preeclampsia
  • Perform frequent monitoring in women < 37 weeks gestation and without severe features, including:
    • blood pressure (twice weekly including in-office assessment of blood pressure ≥ 1 time/week) (Strong recommendation)
    • platelet counts, serum creatinine, and liver enzymes (weekly)
    • urine collection (once weekly) to assess for proteinuria (in women with gestational hypertension)
• Fetal monitoring is recommended during expectant management in women with gestational hypertension or preeclampsia without severe features.
• Measurement of angiogenic factors has been investigated as tool to predict clinical outcomes in women who initially present with early features of preeclampsia; however, no single test has been shown to reliably predict preeclampsia and further study is needed to determine clinical utility.

Management

• Hospitalization is recommended if there is any of the following:
  • systolic blood pressure ≥ 160 mm Hg or diastolic blood pressure ≥ 110 mm Hg (Strong recommendation)
  • development of gestational hypertension or preeclampsia with severe features
  • concerns about adherence to frequent monitoring in women without severe features
• Active management of third stage of labor is recommended, especially in women with thrombocytopenia or a coagulopathy (Strong recommendation).
• Early insertion of an epidural catheter is recommended for control of labor pain in women without contraindications to an epidural (Strong recommendation).
• Blood pressure thresholds for initiation of antihypertensive medications and treatment goal thresholds for hypertensive disorders of pregnancy exist and vary by professional organization.
• Specific management by type of hypertensive disorder
  • In women at moderate-to-high risk of preeclampsia or with chronic hypertension, use low-dose aspirin (75-162 mg daily) starting at 12 weeks gestation and continuing until delivery (Strong recommendation)
  • For management of women with gestational hypertension or preeclampsia without severe features:
    • Indications for expectant management include
      • gestational hypertension, preeclampsia, chronic hypertension, or superimposed preeclampsia without severe features and stable maternal and fetal conditions up until 37 weeks gestation
      • preeclampsia without severe features at 24-33 6/7 weeks gestation but only by a perinatal center capable of caring for very preterm infant (Weak recommendation)
      • chronic hypertension with no additional maternal or fetal complications until 38 weeks gestation if not prescribed antihypertensive medications or until 37 weeks gestation if prescribed maintenance antihypertensive medications
      • chronic hypertension with superimposed preeclampsia and severe features < 34 weeks gestation
    • Delivery is recommended rather than continued observation at ≥ 37 weeks gestation (Strong recommendation).
    • Consider vaginal delivery unless cesarean section is indicated for other obstetric indications (Weak recommendation).
  • For management of women with gestational hypertension or preeclampsia with severe features:
    • Antihypertensive medications (Strong recommendation) and hospitalization are recommended.
    • Delivery is recommended soon after maternal stabilization for women who are ≥ 34 weeks gestation or have unstable maternal or fetal conditions, regardless of gestational age (Strong recommendation).
    • Consider vaginal delivery unless cesarean section is indicated for other obstetric indications (Weak recommendation).
    • Use magnesium sulfate to reduce the risk of eclampsia (Strong recommendation), unless patient has myasthenia gravis.
      • Standard dosing options for magnesium sulfate:
        • 4- to 6-g IV loading dose followed by maintenance dose of 1-2 g/hour for ≥ 24 hours postpartum
        • 4-g IV bolus followed by 1-g/hour infusion
        • 10 g intramuscular loading dose followed by 5 g intramuscular every 4 hours or 1 g/hour infusion until delivery and for ≥ 24 hours postpartum
      • In patients with myasthenia gravis, use magnesium sulfate for treatment of eclamptic seizure with extreme caution and in consultation with obstetric anesthetist and/or neurologist (intubation and ventilation may be required) . Alternative options in these patients include levetiracetam or valproic acid.
    • Give corticosteroids to women receiving expectant management at ≤ 34 weeks gestation to benefit fetal lung maturity (Strong recommendation).
  • For preeclampsia superimposed on chronic hypertension without severe features, consider expectant management until 37 weeks gestation under stable maternal and fetal conditions (Weak recommendation).
• Antihypertensive medications are recommended for urgent control of acute severe hypertension (doses in different guidelines vary) (Strong recommendation):
  • labetalol (in 1 of 2 dosing options):
    • 10- to 20 mg IV bolus, then 20-80 mg every 10-30 minutes up to a maximum cumulative dose of 300 mg
    • constant infusion of 1-2 mg/minute IV
  • nifedipine immediate release 10-20 mg orally, repeated in 30 minutes as needed, then 10-20 mg every 2-6 hours (maximum daily dose 180 mg)
  • hydralazine in 1 of 2 dosing options:
    • 5 mg IV or intramuscularly (IM), then 5-10 mg IV every 20-40 minutes up to a maximum cumulative dose of 20 mg
    • constant infusion of 0.5-10 mg/hour