What is the treatment for hypertensive disorders of pregnancy, including first-line and second-line medications?

Treatment of Hypertensive Disorders of Pregnancy

First-line treatment for hypertensive disorders of pregnancy includes methyldopa, labetalol, and nifedipine, with the goal of maintaining blood pressure between 110-140/85 mmHg. 1 These medications have established safety profiles in pregnancy and are recommended by current guidelines.

Classification of Hypertensive Disorders in Pregnancy

• Chronic hypertension: Pre-existing hypertension before pregnancy or diagnosed before 20 weeks
• Gestational hypertension: New-onset hypertension after 20 weeks without proteinuria
• Preeclampsia: Hypertension after 20 weeks with proteinuria or end-organ dysfunction
• Chronic hypertension with superimposed preeclampsia: Pre-existing hypertension with new-onset proteinuria or worsening hypertension

Blood Pressure Targets and Monitoring

• Severe hypertension (≥160/110 mmHg): Requires urgent treatment in a monitored setting
• Non-severe hypertension (140-159/90-109 mmHg): Target BP 110-140/85 mmHg 2
• Monitoring recommendations:
  • Regular clinic and home BP monitoring
  • Urinalysis at each visit
  • Blood tests (hemoglobin, platelet count, liver enzymes) at minimum at 28 and 34 weeks 1

First-Line Medications

1. Methyldopa

   • Dosing: 250-500 mg orally 2-4 times daily (maximum 3g/day)
   • Advantages: Longest safety record in pregnancy with long-term follow-up studies
   • Disadvantages: May cause sedation and depression 1

2. Labetalol

   • Dosing: 100-400 mg orally twice daily (maximum 2400 mg/day)
   • Advantages: Fewer side effects than methyldopa
   • Disadvantages: Limited long-term fetal outcome data 1, 3

3. Nifedipine (extended-release)

   • Dosing: 30-60 mg once daily
   • Advantages: Once-daily dosing improves adherence
   • Disadvantages: May cause peripheral edema 1

Treatment of Severe Hypertension (≥160/110 mmHg)

For acute severe hypertension requiring immediate intervention:

1. Labetalol (IV): 20 mg IV bolus, then 40 mg 10 minutes later, followed by 80 mg every 10 minutes for 2 additional doses to maximum of 220 mg 2

2. Hydralazine (IV): 5 mg IV bolus, then 10 mg every 20-30 minutes to maximum of 25 mg 2

3. Nifedipine (PO): 10 mg orally, repeat every 20 minutes to maximum of 30 mg (caution when using with magnesium sulfate due to risk of precipitous BP drop) 2

Contraindicated Medications

• ACE inhibitors, ARBs, and direct renin inhibitors: Contraindicated due to fetal toxicity 1
• Atenolol: Contraindicated due to risk of intrauterine growth restriction 1
• Sodium nitroprusside: Should be used only rarely when other treatments fail due to risk of fetal cyanide poisoning 2

Special Considerations for Preeclampsia

• Magnesium sulfate: For seizure prophylaxis in severe preeclampsia or impending eclampsia 2
• Timing of delivery:
  • For preeclampsia at term: Proceed with delivery
  • For gestational hypertension without complications: Delivery can be delayed until 39+6 weeks 1
• Corticosteroids: Should be given between 24+0 and 34+0 weeks gestation for fetal lung maturation 2

Postpartum Management

• Monitor BP and clinical condition at least every 4 hours while awake for at least 3 days postpartum
• Continue antihypertensive medications and withdraw slowly, not abruptly
• Avoid NSAIDs for postpartum analgesia in women with preeclampsia
• Follow up at 3 months to ensure BP, urinalysis, and laboratory abnormalities have normalized 1

Long-term Follow-up

Women with a history of hypertensive disorders in pregnancy have increased lifetime cardiovascular risk and should receive annual cardiovascular risk assessments 1.

By following this structured approach to the management of hypertensive disorders in pregnancy, clinicians can minimize maternal and fetal morbidity and mortality while optimizing long-term outcomes.