What is the target blood pressure goal and medication management for chronic hypertension in pregnancy?

Blood Pressure Management for Chronic Hypertension in Pregnancy

For pregnant women with chronic hypertension, antihypertensive treatment should be initiated and titrated to maintain blood pressure below 140/90 mmHg, with first-line medications including labetalol, methyldopa, or extended-release nifedipine. 1, 2

Target Blood Pressure Goals

The management of chronic hypertension in pregnancy has evolved based on recent evidence:

• Target BP goal: <140/90 mmHg 1, 2
• Do not lower diastolic BP below 80 mmHg to maintain uteroplacental perfusion 2
• Avoid excessive BP lowering as it may compromise fetal growth

This recommendation is supported by the CHAP trial, which demonstrated that treating mild chronic hypertension to a goal of <140/90 mmHg resulted in significant reduction in adverse maternal and fetal outcomes, including preeclampsia with severe features, indicated preterm birth, placental abruption, and fetal/neonatal death 1, 3.

Medication Selection

First-line agents (proven safety in pregnancy):

• Labetalol - preferred beta-blocker for pregnancy
• Methyldopa - long history of safety in pregnancy
• Extended-release nifedipine - calcium channel blocker with established safety profile 2

Medications to AVOID:

• ACE inhibitors and ARBs - contraindicated due to severe fetotoxicity 2, 4
• Diuretics - generally not recommended for blood pressure control in pregnancy (may be used in late pregnancy if needed for volume control) 1
• Atenolol - may be associated with fetal growth restriction when used in early pregnancy

Treatment Algorithm

1. Initial diagnosis: Confirm chronic hypertension (BP ≥140/90 mmHg before pregnancy or before 20 weeks gestation)

2. For BP 140-159/90-109 mmHg:

   • Start with single agent (labetalol, methyldopa, or nifedipine)
   • Titrate dose to achieve target BP <140/90 mmHg
   • Monitor BP weekly in stable patients 2

3. For BP ≥160/110 mmHg (severe hypertension):

   • Immediate hospitalization and treatment required 2, 5
   • IV medications (labetalol, hydralazine) to rapidly reduce BP
   • Target reduction to <160/110 mmHg acutely, then titrate to <140/90 mmHg 2, 5

4. Medication adjustments:

   • If inadequate control with maximum dose of first agent, add second agent
   • If BP remains uncontrolled, consider referral to maternal-fetal medicine specialist

Monitoring During Pregnancy

• Regular BP monitoring (at least weekly in stable patients) 2
• Assess for signs of preeclampsia (proteinuria, symptoms, abnormal labs)
• Monitor fetal growth with serial ultrasounds
• Evaluate for end-organ damage

Important Considerations

• Women with chronic hypertension have increased risk for preeclampsia, fetal growth restriction, placental abruption, and preterm birth 2
• The CHAP trial showed no adverse effects on fetal growth with treatment of mild chronic hypertension 1
• Low-dose aspirin (75-100 mg/day) should be considered for prevention of preeclampsia in women with chronic hypertension 2

Postpartum Management

• Continue monitoring BP for at least 72 hours in hospital and 7-10 days postpartum 1
• Long-term follow-up is recommended as these women have increased lifetime cardiovascular risk 1
• Medications safe for breastfeeding include labetalol, methyldopa, and nifedipine 2

The evidence strongly supports treating chronic hypertension in pregnancy to BP <140/90 mmHg, as this approach has been shown to improve maternal and fetal outcomes without compromising fetal growth 1, 3.