What is the recommended management of hypertension in pregnancy, including treatment thresholds, first‑line oral antihypertensives, acute severe hypertension therapy, monitoring, and delivery timing?

Management of Hypertension in Pregnancy

For hypertension in pregnancy, initiate treatment with oral extended-release nifedipine or labetalol when blood pressure reaches ≥140/90 mmHg, targeting diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg; treat severe hypertension (≥160/110 mmHg) within 60 minutes using immediate-release oral nifedipine, IV labetalol, or IV hydralazine. 1, 2, 3

Treatment Thresholds

Non-Severe Hypertension

• Initiate antihypertensive therapy at BP ≥140/90 mmHg in women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with organ damage or symptoms at any time during pregnancy 3, 4
• For uncomplicated chronic hypertension without these features, treatment begins at BP ≥150/95 mmHg 1, 3
• Home blood pressure monitoring threshold for treatment is ≥135/85 mmHg 3

Severe Hypertension (Hypertensive Emergency)

• BP ≥160/110 mmHg sustained for ≥15 minutes constitutes a hypertensive emergency requiring immediate treatment 1, 3, 5, 6
• Treatment must be initiated within 30-60 minutes of the first severe reading to prevent maternal stroke 2, 6
• This lower threshold compared to non-pregnant patients reflects the increased stroke risk in pregnancy 6

Blood Pressure Targets

• Target diastolic BP: 85 mmHg 1, 3, 7
• Target systolic BP: 110-140 mmHg (some guidelines accept <160 mmHg as minimum) 1, 3
• Reduce or cease antihypertensives if diastolic BP falls <80 mmHg to avoid maternal hypotension and compromised uteroplacental perfusion 1, 7

First-Line Oral Antihypertensives for Chronic Control

Extended-Release Nifedipine

• Preferred first-line agent due to once-daily dosing, improving adherence 2, 3
• Dosing: up to 120 mg daily for maintenance therapy 1, 2
• Established safety data throughout pregnancy 2
• Never use sublingual nifedipine due to risk of uncontrolled hypotension and maternal myocardial infarction 2, 1

Labetalol

• Equally effective as nifedipine with comparable safety profile 2, 3
• Dosing: 100 mg twice daily initially, titrated up to maximum 2400 mg/day in divided doses 2
• Requires TID or QID dosing due to accelerated metabolism in pregnancy 2
• Contraindicated in reactive airway disease (asthma/COPD) 2
• Potential risks include neonatal bradycardia and small-for-gestational-age infants 2

Methyldopa

• Longest documented safety record with child follow-up to 7.5 years 1, 3
• Less favorable side-effect profile compared to nifedipine and labetalol 2
• Must be switched postpartum due to association with postpartum depression 1, 2, 3

Second-Line Agents

• Hydralazine and prazosin are acceptable second or third-line options 1

Acute Management of Severe Hypertension

First-Line Agents for Acute Severe Hypertension (≥160/110 mmHg)

Immediate-Release Oral Nifedipine:

• 10-20 mg orally (never sublingual), repeat every 20-30 minutes if BP remains severely elevated 1, 2, 5
• Maximum 30 mg in the first hour 1, 2
• May work fastest among available agents 8
• Avoid concurrent use with magnesium sulfate due to risk of precipitous hypotension and myocardial depression 1, 2, 3

Intravenous Labetalol:

• 20 mg IV bolus, repeat with escalating doses (40 mg, 80 mg) every 10 minutes 2
• Maximum single dose: 300 mg 2
• Oral loading: 200 mg if IV access unavailable 2

Intravenous Hydralazine:

• 5-10 mg IV bolus, repeat as needed 2, 5, 6
• Equally effective as labetalol and nifedipine 5, 6

Target for Acute Management

• Reduce systolic BP to 140-150 mmHg and diastolic BP to 90-100 mmHg 5, 7
• Avoid excessive reduction to prevent placental hypoperfusion 5

Absolutely Contraindicated Medications

ACE inhibitors, angiotensin receptor blockers (ARBs), direct renin inhibitors, and mineralocorticoid receptor antagonists are strictly contraindicated throughout pregnancy due to severe fetotoxicity, renal dysgenesis, and oligohydramnios, with effects particularly pronounced in the second and third trimesters 2, 3, 4

Monitoring Requirements

Maternal Monitoring in Preeclampsia

• BP monitoring: continuous or frequent depending on severity 1
• Clinical assessment: including evaluation for clonus 1
• Laboratory tests twice weekly: hemoglobin, platelet count, liver transaminases (AST, ALT, LDH), creatinine, uric acid 1
• Repeated proteinuria assessment if not already present 1

Fetal Monitoring

• Ultrasound assessment of fetal biometry, amniotic fluid, and umbilical artery Doppler at first diagnosis 1, 3
• Repeat every 2 weeks if initial assessment normal 1, 3
• More frequent monitoring (amniotic fluid and Doppler) in presence of fetal growth restriction 1
• For absent end-diastolic flow before 34 weeks: daily cardiotocograph, twice-weekly umbilical artery Doppler 3

Home Blood Pressure Monitoring

• Strongly recommended during pregnancy and postpartum 1, 3
• In absence of severe hypertension, rely on average BP over several days rather than single readings 1

Delivery Timing

Gestational Hypertension Without Preeclampsia

• Delivery can be delayed until 39+6 weeks if BP remains controlled, fetal monitoring reassuring, and preeclampsia has not developed 3, 1

Preeclampsia at Term

• Recommend delivery 3

Severe Preeclampsia

• Deliver promptly regardless of gestational age, either vaginally or by cesarean section based on obstetric indications 1

Uncontrollable Hypertension

• Inability to control BP despite ≥3 classes of antihypertensives in appropriate doses constitutes an indication for delivery regardless of gestational age 7

Eclampsia

• Delivery soon after maternal stabilization 1

Magnesium Sulfate for Seizure Prophylaxis

• Indicated for women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs or symptoms 1, 3
• Loading dose: 4 g IV or 10 g IM, followed by 5 g IM every 4 hours or 1 g/h infusion 1
• Continue until delivery and for at least 24 hours postpartum 1
• Do not administer concurrently with calcium channel blockers due to risk of severe hypotension and myocardial depression 1, 2, 3

Postpartum Management

Immediate Postpartum Period

• Continue antihypertensive regimen immediately after delivery for hemodynamically stable patients 2
• Switch methyldopa to nifedipine or labetalol before discharge due to depression risk 1, 2, 3
• BP typically worsens between postpartum days 3-6; maintain therapy during this window 2, 3
• Treat urgently if BP ≥160/110 mmHg lasting >15 minutes 1, 2

Blood Pressure Monitoring

• Check BP at least 4-6 times daily during first 3 days postpartum 2, 3
• Implement home BP monitoring after discharge with at least two readings per day 2

Medication Tapering

• Reduce or stop antihypertensives when diastolic BP consistently <80 mmHg 2
• When both labetalol and nifedipine prescribed, taper labetalol first due to nifedipine's superior once-daily adherence 2
• Adjust only one medication at a time with 3-7 day intervals between changes 2

Breastfeeding-Compatible Medications

• Labetalol and extended-release nifedipine are safe for breastfeeding 1, 2, 3
• Enalapril is preferred ACE inhibitor postpartum (with documented contraception plan) 2
• Avoid diuretics as they may reduce milk production 1, 2

Follow-Up Timeline

• Review within 1 week if still requiring antihypertensives at discharge 2
• 3-month postpartum visit to confirm BP, urinalysis, and laboratory normalization 2, 3
• Persistent hypertension beyond 12 weeks warrants evaluation for chronic hypertension and secondary causes 2, 8

Prevention Strategies

Low-Dose Aspirin

• 75-150 mg daily from week 12 to weeks 36-37 for women at high or moderate risk of preeclampsia 1, 2
• For women with history of early-onset preeclampsia, start pre-pregnancy or before 16 weeks, continue until delivery 3

Calcium Supplementation

• ≥1 g daily reduces preeclampsia risk, particularly in women with low calcium diet 1, 2, 3

Corticosteroids for Fetal Lung Maturity

• Consider for all women with preeclampsia at ≤34 weeks gestation 1
• For gestational hypertension at ≤34 weeks, only if delivery considered within next 7 days 1

Long-Term Cardiovascular Risk

• Women with gestational hypertension or preeclampsia have ≈4-fold increased risk of chronic hypertension and >2-fold increased risk of ischemic heart disease 2, 3
• Annual lifelong medical review recommended for cardiovascular risk assessment 2, 3
• Counsel on lifestyle modifications: weight management, physical activity, heart-healthy diet, smoking cessation 2, 3

Critical Pitfalls to Avoid

• Never use short-acting nifedipine for maintenance therapy—reserve exclusively for acute severe hypertension 2
• Never use sublingual nifedipine—risk of uncontrolled hypotension and maternal MI 1, 2
• Never combine calcium channel blockers with magnesium sulfate—risk of precipitous hypotension 1, 2, 3
• Never continue methyldopa postpartum—switch before discharge due to depression risk 1, 2, 3
• Never aim for diastolic BP <80 mmHg—no benefit and may cause symptomatic hypotension 2, 7
• Never abruptly discontinue all antihypertensives at discharge—BP often rises in first postpartum week 2
• Avoid atenolol specifically—higher risk of fetal growth restriction compared to other beta-blockers 2, 3
• Do not use plasma volume expansion routinely in preeclampsia 1