Management of Pregnancy-Induced Hypertension (PIH)
The management of pregnancy-induced hypertension requires prompt antihypertensive treatment when blood pressure reaches ≥140/90 mmHg in women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with organ damage or symptoms. 1
Classification of Hypertension in Pregnancy
- Pre-existing (chronic) hypertension: Hypertension (≥140/90 mmHg) that predates pregnancy or develops before 20 weeks gestation
- Gestational hypertension: Pregnancy-induced hypertension without proteinuria developing after 20 weeks
- Pre-eclampsia: Gestational hypertension with proteinuria (≥0.3 g/day or ACR ≥30 mg/mmol) or other maternal organ dysfunction
- Pre-existing hypertension with superimposed gestational hypertension with proteinuria 2, 1
Diagnostic Evaluation
- Confirm diagnosis with BP measurements on at least two separate occasions or at least 15 minutes apart in severe hypertension
- Assess for proteinuria (>0.3 g/24 h or ACR ≥30 mg/mmol)
- Screen for signs of end-organ damage:
Management Approach
Non-Pharmacological Management
- Indicated for mild hypertension (SBP 140-149 mmHg or DBP 90-99 mmHg)
- Includes:
- Close supervision and limitation of activities
- Some bed rest in the left lateral position
- Normal diet without salt restriction
- Regular monitoring of maternal and fetal parameters 2
Preventive Measures
- Low-dose aspirin (75-100 mg/day) prophylactically in women with history of early-onset (<28 weeks) pre-eclampsia
- Weight management:
- Avoid excessive weight gain during pregnancy
- For normal BMI (<25 kg/m²): 11.2-15.9 kg weight gain recommended
- For overweight (BMI 25-29.9 kg/m²): 6.8-11.2 kg weight gain recommended
- For obese (BMI ≥30 kg/m²): <6.8 kg weight gain recommended 2
Pharmacological Management
Indications for Treatment
- Start antihypertensive treatment when:
Target Blood Pressure
- Target BP <140/90 mmHg but not below 80 mmHg for diastolic BP 1
First-Line Medications
- Methyldopa: 250-500 mg divided twice daily or more frequently
- Labetalol: 200-800 mg divided twice daily or more frequently
- Calcium channel blockers:
- Nifedipine XR: 30-60 mg once daily
- Amlodipine: 5-10 mg once daily 1
Hypertensive Emergency Management
- Defined as SBP ≥160 mmHg or DBP ≥110 mmHg with acute hypertension-mediated organ damage
- Requires hospitalization
- Intravenous options:
- Labetalol (first choice)
- Oral methyldopa
- Oral nifedipine
- Avoid intravenous hydralazine (associated with more perinatal adverse effects)
- Sodium nitroprusside is reserved for hypertensive crises but carries risk of fetal cyanide poisoning
- Nitroglycerin is the drug of choice in pre-eclampsia with pulmonary edema 2
Contraindicated Medications
- Absolutely contraindicated: ACE inhibitors, ARBs, direct renin inhibitors (risk of fetal toxicity)
- Use with caution:
Delivery and Postpartum Care
- For gestational hypertension without complications, delivery can be delayed until 39+6 weeks if BP is controlled and fetal monitoring is reassuring
- Close monitoring for 24-72 hours postpartum as hypertension may worsen between days 3-6
- Review within 1 week if still requiring antihypertensives at hospital discharge
- Continue antihypertensive treatment after delivery if needed 1
Long-Term Follow-Up
- Women with history of PIH have increased future risk of:
- Hypertension (nearly four times higher risk)
- Ischemic heart disease (more than double risk)
- Stroke
- Diabetes mellitus 1
- Regular monitoring of blood pressure and metabolic factors is essential
- Periodic measurement of fasting lipids and blood glucose
- Maintain healthy lifestyle with regular aerobic exercise 1
Special Considerations
- Multidisciplinary team approach recommended for complex cases
- Risk stratification based on severity of hypertension and presence of comorbidities
- Early recognition and management of complications is crucial to improve maternal and fetal outcomes 1