What is the management of pregnancy-induced hypertension?

Management of Pregnancy-Induced Hypertension

For pregnancy-induced (gestational) hypertension, initiate antihypertensive treatment at BP ≥140/90 mmHg using methyldopa, labetalol, or long-acting nifedipine as first-line agents, targeting systolic BP 110-140 mmHg and diastolic BP 85-90 mmHg, with urgent treatment required for BP ≥160/110 mmHg to prevent maternal stroke. 1, 2

Classification and Initial Assessment

Pregnancy-induced hypertension (gestational hypertension) develops after 20 weeks of gestation without proteinuria and complicates 6-7% of pregnancies. 3 This differs from pre-eclampsia, which includes clinically significant proteinuria (≥0.3 g/day in 24-hour urine or ≥30 mg/mmol urinary creatinine). 3, 1

Critical distinction: Approximately 25% of women with gestational hypertension will progress to preeclampsia, requiring close monitoring. 4

Treatment Thresholds and Targets

When to Initiate Pharmacological Treatment

Definite indication for treatment: BP ≥150/95 mmHg in any pregnant woman. 2

Lower threshold (≥140/90 mmHg) recommended for: 1, 2

• Women with gestational hypertension with or without proteinuria
• Pre-existing hypertension with superimposed gestational hypertension
• Hypertension with subclinical organ damage or symptoms

Blood Pressure Targets

Target range: Systolic BP 110-140 mmHg and diastolic BP 85-90 mmHg. 1, 2

Critical caveat: Never reduce diastolic BP below 80 mmHg, as this impairs uteroplacental perfusion and compromises fetal development. 2 This represents the key tension in managing pregnancy hypertension—balancing maternal protection against fetal well-being.

Non-Pharmacological Management

For BP 140-150/90-99 mmHg, consider initial non-pharmacological approach: 3

• Close supervision with BP monitoring at least twice weekly initially, then weekly once stable 2
• Activity limitation and some bed rest in left lateral position 3
• Normal diet without salt restriction, particularly close to delivery (salt restriction may induce low intravascular volume) 3
• Short-term hospitalization may be required to confirm diagnosis and rule out severe pre-eclampsia 3

Preventive Measures

Calcium supplementation: At least 1 g daily during pregnancy almost halved the risk of pre-eclampsia, with greatest effect in high-risk women. 3

Low-dose aspirin (75-100 mg/day): Used prophylactically in women with history of early-onset (<28 weeks) pre-eclampsia, administered at bedtime starting pre-pregnancy or from diagnosis but before 16 weeks gestation, continued until delivery. 3

Avoid: Fish oil supplementation and vitamin/nutrient supplements have no role in prevention. 3 Weight reduction is not recommended during pregnancy in obese women. 3

First-Line Pharmacological Agents

Three equally acceptable first-line options: 1, 2

Methyldopa

• Traditional first choice with longest safety record (7.5-year infant follow-up data) 3
• Caution: Use with caution in women at risk for postpartum depression 2
• Appears in breast milk; exercise caution in nursing mothers 5

Labetalol

• Efficacy comparable to methyldopa 3
• Can be given IV for severe hypertension 3
• Small amounts (0.004% of maternal dose) excreted in breast milk 6

Long-Acting Nifedipine

• Equally acceptable as first-line agent 1, 2
• Critical warning: Avoid short-acting immediate-release nifedipine except in low-resource settings, as it can induce uncontrolled hypotension, particularly when combined with magnesium sulfate, resulting in fetal compromise 3
• Excreted in human milk; nursing mothers advised not to breastfeed 7

Second/Third-Line Agents

Hydralazine and prazosin recommended as second or third-line agents. 1

Metoprolol also recommended, though atenolol and metoprolol appear safe only in late pregnancy. 8

Management of Severe Hypertension (≥160/110 mmHg)

This is a hypertensive emergency requiring immediate hospitalization and urgent treatment within 15 minutes in a monitored setting to prevent maternal stroke. 3, 4

Immediate Goal

Decrease mean BP by 15-25%, targeting systolic BP 140-150 mmHg and diastolic BP 90-100 mmHg. 3

First-Line Agents for Acute Severe Hypertension

IV Labetalol: 20 mg IV bolus, then 40-80 mg every 10 minutes (maximum 300 mg total). 2

IV Hydralazine: Still widely used, particularly in North America, though associated with maternal hypotension, greater risk of caesarean section, placental abruption, maternal oliguria, and fetal tachycardia—requires close monitoring. 3

Oral nifedipine (if immediate-release not available and IV access not established): 200 mg labetalol or 1.0-1.5 g methyldopa can be administered orally. 3

Alternative IV agents: Urapidil or nicardipine. 3

Last resort only: Sodium nitroprusside for extreme emergencies when BP cannot be controlled by other means, for shortest possible time (risk of fetal cyanide poisoning and increased maternal intracranial pressure). 3

Special Situation: Pre-eclampsia with Pulmonary Edema

Drug of choice: IV nitroglycerin (glycerol trinitrate) 5 mg/min, gradually increased every 3-5 min to maximum 100 mg/min. 3

Strictly Contraindicated Medications

Never use in pregnancy: ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated due to severe fetotoxicity, particularly in second and third trimesters. 3, 2 If taken inadvertently in first trimester, switch immediately to another medication and provide close monitoring including fetal ultrasound. 3

Monitoring Protocol

Maternal monitoring: 2

• BP checks at least twice weekly initially, then weekly once stable
• Proteinuria assessment at each visit
• Baseline laboratory assessment including CBC, liver enzymes, serum creatinine, electrolytes, and uric acid 4

Fetal monitoring: Antenatal testing for fetal well-being. 9

Maternal early warning criteria requiring immediate attention: 3

• Systolic BP >160 mmHg or <90 mmHg
• Diastolic BP >100 mmHg
• Non-remitting headache in patient with hypertensive disease
• Shortness of breath
• Changed mental status

Delivery Planning

For stable gestational hypertension: Plan delivery at 37 weeks and 0 days. 1, 2

For pre-eclampsia with severe features: Deliver promptly regardless of gestational age after immediate stabilization with magnesium sulfate for seizure prophylaxis. 2, 9

If adverse conditions present (visual disturbances, coagulation abnormalities, fetal distress): Induce delivery. 1

Postpartum Management

Critical period: Hypertensive disorders can worsen or initially present after delivery, accounting for up to 44% of pregnancy-related deaths in first six days postpartum. 9

Monitoring schedule: 4

• BP recorded shortly after birth
• Again within 6 hours if normal
• Follow-up at 48-72 hours after birth
• Again at 7-14 days
• At 6 weeks postpartum

Long-Term Follow-Up

Annual medical review lifelong recommended for women with gestational hypertension or preeclampsia due to increased lifetime cardiovascular risk. 1, 2, 4 These women have increased risk of hypertension and stroke in later life, requiring lifestyle modifications, regular BP monitoring, and control of metabolic factors. 1