What is the recommended management for hypertension in pregnancy?

Management of Hypertension in Pregnancy

For hypertension in pregnancy, initiate antihypertensive treatment when blood pressure is consistently ≥140/90 mmHg, targeting a diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1

Blood Pressure Thresholds and Treatment Initiation

When to Start Treatment

• Start pharmacological treatment when office BP is ≥140/90 mmHg (or home BP ≥135/85 mmHg) in both chronic hypertension and gestational hypertension 1, 2
• This applies to:
  • Women with gestational hypertension (new onset after 20 weeks) 1, 2
  • Women with chronic hypertension 1
  • Women with preeclampsia 1

Target Blood Pressure

• Aim for diastolic BP of 85 mmHg and systolic BP between 110-140 mmHg 1, 2, 3
• Do not lower diastolic BP below 80 mmHg—reduce or stop medications if this occurs to avoid placental hypoperfusion 1, 3
• The upper limit should remain below 140/90 mmHg 1

Urgent Treatment of Severe Hypertension

BP ≥160/110 mmHg requires immediate treatment in a monitored setting as this represents a hypertensive emergency with increased stroke risk 1, 2, 3

Acute Management Options

• Oral nifedipine (immediate-release) 1, 3
• Intravenous labetalol 1, 3
• Intravenous hydralazine 1, 3

Goal for Acute Treatment

• Reduce systolic BP to 140-150 mmHg and diastolic BP to 90-100 mmHg 3

First-Line Antihypertensive Medications

The preferred agents for ongoing BP control in pregnancy are: 1, 2

1. Methyldopa (drug of choice, most extensively studied) 1, 4
2. Labetalol 1, 2, 4
3. Long-acting nifedipine (extended-release formulations) 1, 2

Second-Line Agents

• Oxprenolol 1
• Hydralazine 1, 3
• Prazosin 1, 3

Contraindicated Medications

• ACE inhibitors and angiotensin receptor blockers are absolutely contraindicated due to fetopathy risk 1, 4, 5
• Atenolol should be avoided due to concerns about fetal growth restriction 4, 5

Classification and Monitoring Strategy

Types of Hypertension in Pregnancy

The approach differs based on classification: 1

Chronic Hypertension:

• Hypertension present before pregnancy or diagnosed before 20 weeks gestation 1
• Requires baseline laboratory assessment: hemoglobin, platelet count, liver enzymes, uric acid, creatinine, and urinalysis 1, 2

Gestational Hypertension:

• New-onset hypertension after 20 weeks without proteinuria 1, 2
• Critical caveat: 25% will progress to preeclampsia, especially if diagnosed before 34 weeks 1, 2

Preeclampsia:

• Gestational hypertension with proteinuria or other end-organ dysfunction 1

Maternal Monitoring Requirements

For Gestational Hypertension: 1, 2

• Urinalysis at each visit to detect proteinuria 1, 2
• Laboratory tests (hemoglobin, platelet count, liver transaminases, uric acid, creatinine) at minimum at 28 and 34 weeks 1, 2
• Clinical assessment for symptoms: headache, visual disturbances, epigastric pain 1
• Check for clonus (hyperreflexia suggests progression) 2

For Chronic Hypertension:

• Same monitoring as gestational hypertension to detect superimposed preeclampsia 1
• More frequent assessment if uric acid is elevated 1

Fetal Monitoring

• Begin ultrasound assessment at 26 weeks gestation 1, 2
• Repeat every 2-4 weeks if fetal biometry is normal 1, 2
• Increase frequency if fetal growth restriction is suspected 1, 2

Indications for Hospitalization

Admit to hospital for: 2, 3

• BP ≥160/110 mmHg (severe hypertension) 2, 3
• Development of preeclampsia features (proteinuria, symptoms, laboratory abnormalities) 2
• Neurological signs or symptoms 2
• Inability to control BP with ≥3 antihypertensive drug classes at appropriate doses 3

Timing of Delivery

Gestational Hypertension Without Preeclampsia

• Delivery can be delayed until 39+6 weeks if: 1, 2
  • BP remains controlled 1, 2
  • Fetal monitoring is reassuring 1, 2
  • Preeclampsia has not developed 1, 2
• Optimal timing appears to be 38-39 weeks based on retrospective data, though this requires confirmation in randomized trials 1, 2

Preeclampsia

• Delivery at term (≥37 weeks) is recommended 1
• Earlier delivery may be necessary based on maternal or fetal indications 1

Uncontrollable Hypertension

• Inability to control BP despite ≥3 drug classes is an absolute indication for delivery regardless of gestational age 3

Special Considerations for Preeclampsia

Magnesium Sulfate

• Use MgSO4 for seizure prophylaxis in preeclampsia (especially severe preeclampsia) and for treatment of eclampsia 1
• Loading dose: 4g IV or 10g IM 1
• Maintenance: 5g IM every 4 hours or 1g/hour IV infusion 1
• Continue until delivery and for at least 24 hours postpartum 1

Corticosteroids

• Administer antenatal corticosteroids between 24+0 and 34+0 weeks if delivery is likely within 7 days 1
• May be given up to 38+0 weeks for elective cesarean section 1

Postpartum Management

• Record BP shortly after birth and again within 6 hours 1
• Continue antihypertensive treatment as needed to maintain BP <140/90 mmHg 1
• Do not discharge until vital signs are stable for at least 24 hours 1
• Follow-up visits at 48-72 hours, 7-14 days, and 6 weeks postpartum 1
• Educate about danger signs: severe headache, visual disturbances, nausea, vomiting, epigastric pain 1

Long-Term Cardiovascular Risk

• Women with gestational hypertension or preeclampsia have increased lifetime cardiovascular risk 1, 6, 5, 7
• Recommend annual medical review lifelong 1
• Encourage healthy lifestyle: exercise, healthy eating, achieve ideal body weight by 12 months postpartum 1
• Limit interpregnancy weight gain 1

Common Pitfalls to Avoid

1. Do not wait for BP ≥160/110 mmHg to initiate treatment—start at ≥140/90 mmHg to prevent progression to severe hypertension 1
2. Do not lower diastolic BP below 80 mmHg—this may compromise placental perfusion 1, 3
3. Do not assume gestational hypertension is benign—at least 25% progress to preeclampsia 1, 2
4. Do not use ACE inhibitors, ARBs, or atenolol in pregnancy 1, 4, 5
5. Do not delay delivery when BP cannot be controlled with ≥3 medications—this is an absolute maternal indication for delivery 3