What is the initial management approach for hypertension in pregnancy?

Initial Management of Hypertension in Pregnancy

The initial management approach for hypertension in pregnancy should include non-pharmacological interventions for mild hypertension (140-150/90-99 mmHg) and pharmacological treatment with methyldopa or labetalol for blood pressure ≥150/95 mmHg or ≥140/90 mmHg with organ damage or symptoms. 1

Classification of Hypertension in Pregnancy

Hypertension in pregnancy is classified into four main categories:

1. Pre-existing hypertension: BP ≥140/90 mmHg before pregnancy or <20 weeks gestation, persisting >42 days postpartum
2. Gestational hypertension: New-onset hypertension after 20 weeks gestation without proteinuria
3. Preeclampsia: Gestational hypertension with proteinuria (≥0.3 g/day) or other maternal organ dysfunction
4. Pre-existing hypertension with superimposed gestational hypertension with proteinuria 1

Initial Diagnostic Evaluation

• Blood pressure measurement: Use validated devices for pregnancy and preeclampsia
• Laboratory tests:
  • Urine analysis for proteinuria (dipstick >1+ should be followed by UACR)
  • Complete blood count
  • Liver enzymes
  • Serum creatinine and uric acid
  • If proteinuria present: 24-hour urine collection or spot UACR
• Ultrasound: Kidneys and adrenals if secondary hypertension suspected
• Doppler ultrasound: Of uterine arteries after 20 weeks to detect risk for preeclampsia 1

Management Algorithm

1. Non-pharmacological Management (BP 140-150/90-99 mmHg)

• Close supervision and monitoring
• Limitation of activities
• Some bed rest in left lateral position
• Normal diet without salt restriction (salt restriction may reduce intravascular volume)
• Regular physical activity as tolerated 1

2. Pharmacological Management

When to initiate medication:

• BP persistently ≥150/95 mmHg in all pregnant women 1
• BP ≥140/90 mmHg in women with:
  • Gestational hypertension (with/without proteinuria)
  • Pre-existing hypertension with superimposed gestational hypertension
  • Hypertension with organ damage or symptoms 1
• Severe hypertension (≥160/110 mmHg) requires immediate treatment 1

First-line medications:

• Methyldopa: Drug of choice in pregnancy with established safety record 1, 2
• Labetalol: Efficacy comparable to methyldopa, can be given IV for severe hypertension 1
• Nifedipine (long-acting): Calcium channel blocker with good safety profile 3

Medications to avoid:

• ACE inhibitors
• Angiotensin receptor blockers (ARBs)
• Direct renin inhibitors
• These are contraindicated due to severe fetotoxicity 1

Prevention of Preeclampsia

For women at high risk of preeclampsia (previous hypertensive pregnancy, chronic kidney disease, autoimmune disease, diabetes, chronic hypertension):

• Low-dose aspirin: 75-162 mg daily from weeks 12-36 1
• Calcium supplementation: 1.2-2.5 g/day if dietary intake is low (<600 mg/day) 1

Monitoring and Follow-up

• Regular BP monitoring (frequency based on severity)
• Assessment of maternal symptoms (headache, visual disturbances, epigastric pain)
• Fetal growth monitoring
• Laboratory tests to monitor for preeclampsia
• Evaluation for organ damage in severe cases 1

Important Considerations and Pitfalls

1. Do not abruptly discontinue antihypertensives: Women with pre-existing hypertension should continue their current medication except for ACE inhibitors, ARBs, and direct renin inhibitors, which must be switched before pregnancy or immediately upon diagnosis 1

2. Beware of masked hypertension: Pre-existing hypertension may appear to normalize in early pregnancy due to physiological BP drop in the first trimester 1

3. Monitor for progression: Gestational hypertension can progress to preeclampsia, requiring vigilant monitoring for proteinuria and other signs of organ dysfunction 1

4. Postpartum monitoring: Continue monitoring BP for at least 3 days postpartum as eclampsia can develop for the first time in this period 1

5. Long-term follow-up: Women with hypertensive disorders in pregnancy have increased lifetime risk of cardiovascular disease and require annual medical review 1, 3