What is the initial treatment approach for mild Pregnancy-Induced Hypertension (PIH)?

Treatment of Mild Pregnancy-Induced Hypertension

For mild PIH (BP 140-149/90-99 mmHg), initiate antihypertensive medication targeting BP <140/90 mmHg while maintaining diastolic BP ≥80 mmHg, using methyldopa, labetalol, or extended-release nifedipine as first-line agents. 1, 2

Blood Pressure Thresholds and Treatment Goals

Pharmacological treatment should be initiated when BP is persistently ≥140/90 mmHg in pregnant women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or any hypertension with organ dysfunction or symptoms. 2 This represents a shift from older recommendations that suggested treatment only at higher thresholds (≥150/95 mmHg for uncomplicated chronic hypertension). 2

The target BP should be:

• Systolic: 110-140 mmHg 3, 1
• Diastolic: 80-85 mmHg (not below 80 mmHg) 3, 1, 2

This approach is supported by the CHAP trial, which demonstrated that treating to <140/90 mmHg reduced composite adverse outcomes (preeclampsia with severe features, medically indicated preterm birth <35 weeks, placental abruption, or fetal/neonatal death) from 37.0% to 30.2% compared to withholding treatment until severe hypertension developed. 3

First-Line Pharmacological Options

Methyldopa

• Has the longest safety record with documented 7.5-year infant follow-up data 2
• Starting dose: 250 mg two to three times daily, with dose increases preferably at intervals of not less than 2 days 4
• Usual maintenance: 500 mg to 2 g daily in divided doses 4
• Maximum dose: 3 g daily 4
• Start dose increases in the evening to minimize sedation 4

Labetalol

• Efficacy comparable to methyldopa with a strong safety profile 1, 2, 5
• Provides both alpha and beta-blockade 1
• Particularly useful when methyldopa is ineffective or not tolerated 2

Extended-Release Nifedipine

• Strong safety profile with once-daily dosing that improves adherence 2
• Should only be used after 20 weeks of gestation 6
• Provides effective BP control without compromising fetal circulation when used appropriately 2

Non-Pharmacological Management

All pregnant women with mild PIH should receive comprehensive lifestyle interventions alongside pharmacological therapy:

• Low to moderate-intensity exercise for all pregnant women without contraindications 1, 2
• Calcium supplementation ≥1 g daily, particularly beneficial in high-risk women 1, 2
• Low-dose aspirin (75-100 mg daily) started before 16 weeks gestation in women with history of early-onset pre-eclampsia (<28 weeks) 2
• Sodium restriction (<2,300 mg/day) and DASH-style eating pattern 3

Critical Monitoring Parameters

Maternal monitoring should include:

• BP monitoring at home and in clinic 3
• Clinical assessment including clonus 3
• Minimum twice weekly blood tests: hemoglobin, platelet count, liver function, renal function including uric acid 3
• Repeated assessments for proteinuria if not already present 3

Fetal monitoring should include:

• Initial assessment to confirm fetal well-being 3
• Serial ultrasound surveillance if fetal growth restriction is present 3

Common Pitfalls and Contraindications

Absolutely contraindicated medications:

• ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated throughout pregnancy due to severe fetotoxicity 3, 2, 5
• Women of childbearing potential on these agents must switch to pregnancy-safe alternatives before conception 3

Important caveats:

• Avoid letting diastolic BP fall below 80 mmHg, as this may compromise uteroplacental perfusion 3, 1, 2
• Atenolol should be avoided in early pregnancy but may be used in late pregnancy 5
• Do not abruptly cease antihypertensive medications, as eclamptic seizures may develop 2

When to Escalate Care

Urgent hospitalization and treatment are required when:

• BP reaches ≥160/110 mmHg (severe hypertension) 3, 1, 2
• Development of proteinuria with severe hypertension 3
• Neurological signs or symptoms (severe headache, visual scotomata) 3
• Progressive thrombocytopenia or abnormal liver/renal function 3

For severe hypertension, intravenous labetalol is the preferred option, with alternatives including intravenous hydralazine or oral nifedipine. 3, 1

Long-Term Implications

Women with PIH have significantly increased long-term cardiovascular risk and require:

• Review at 3 months postpartum to ensure BP, urinalysis, and laboratory abnormalities have normalized 2
• Annual medical review lifelong for cardiovascular risk assessment 2
• Lifestyle modifications to reduce future cardiovascular complications 3