What is the management approach for a pregnant patient with hypertension?

Management of Hypertension in Pregnancy

Initiate antihypertensive treatment when blood pressure reaches ≥140/90 mmHg in pregnant women, targeting systolic BP 110-140 mmHg and diastolic BP 85 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1, 2, 3

Blood Pressure Thresholds and Treatment Goals

• Start pharmacological treatment at BP ≥140/90 mmHg for women with gestational hypertension (new-onset after 20 weeks), chronic hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms 1, 2, 3

• For chronic hypertension without these features, treatment may begin at ≥150/95 mmHg, though the more conservative ≥140/90 mmHg threshold is increasingly recommended 2, 3

• Target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg during treatment to balance maternal protection with uteroplacental perfusion 1, 2, 3

• Home BP monitoring is useful when available; use ≥135/85 mmHg as the threshold for treatment initiation with home readings 4

Severe Hypertension: Immediate Management

BP ≥160/110 mmHg constitutes a hypertensive emergency requiring immediate hospitalization and treatment within 15 minutes to prevent maternal stroke. 1, 2, 3

• First-line agents for acute severe hypertension include:

  • Oral immediate-release nifedipine (preferred for rapid onset) 1, 2, 3
  • Intravenous labetalol 1, 2, 3
  • Intravenous hydralazine 1, 3

• Treat in a monitored setting with continuous BP assessment 1, 2

First-Line Antihypertensive Medications for Chronic Control

The three preferred agents for ongoing BP control during pregnancy are methyldopa, labetalol, and long-acting nifedipine. 1, 2, 3

Methyldopa

• Considered the drug of choice based on long-term safety data (7.5 years infant follow-up) 4
• Safe throughout pregnancy with no evidence of fetal harm 5
• Avoid postpartum due to risk of postnatal depression 2, 3
• May cause false-positive catecholamine levels; use VMA testing if pheochromocytoma suspected 5

Labetalol

• Efficacy comparable to methyldopa 4, 6
• Can be given intravenously for severe hypertension 4
• Do not use concomitantly with calcium channel blockers due to severe hypotension risk 2, 7
• Small amounts excreted in breast milk (0.004% of maternal dose) 7

Long-Acting Nifedipine

• Effective for both chronic control and acute management (immediate-release form) 1, 2, 3
• Calcium supplementation (≥1 g daily) may enhance prevention of preeclampsia 4, 3

Alternative Agents

• Metoprolol is also recommended as an alternative beta-blocker 4, 3
• Oxprenolol, diltiazem, prazosin, and hydralazine are usually second or third-line agents 4

Absolutely Contraindicated Medications

ACE inhibitors, angiotensin receptor blockers (ARBs), and direct renin inhibitors are strictly contraindicated due to severe fetotoxicity, particularly in the second and third trimesters. 4, 2, 3

• If taken inadvertently in the first trimester, switch immediately to alternative medication and perform close fetal ultrasound monitoring 4

Classification and Diagnostic Approach

Chronic Hypertension

• Defined as hypertension present before pregnancy or diagnosed before 20 weeks gestation 1, 2
• Obtain baseline laboratory assessment including hemoglobin, platelet count, liver transaminases, uric acid, and creatinine 4
• Key risks include superimposed preeclampsia, fetal growth restriction, and accelerated maternal hypertension 4

Gestational Hypertension

• New-onset hypertension at or after 20 weeks without proteinuria 1, 2
• 25% will progress to preeclampsia 1
• Monitor for preeclampsia development with urinalysis at each visit and blood tests at minimum 28 and 34 weeks 4
• Assess fetal well-being with ultrasound from 26 weeks, then every 2-4 weeks if normal 4

White-Coat Hypertension

• When confirmed, manage with regular home BP assessments without antihypertensives up to office BP levels of 160/110 mmHg 4

Indications for Hospitalization

Admit immediately for: 1, 2

• BP ≥160/110 mmHg (severe hypertension)
• Development of preeclampsia features (proteinuria, end-organ dysfunction)
• Neurological signs or symptoms (visual disturbances, severe headache, altered mental status)
• Inability to control BP with ≥3 antihypertensive drug classes

Fetal Monitoring in Hypertensive Disorders

• Assess fetal growth with ultrasound from 26 weeks gestation, then every 2-4 weeks if normal 4
• If elevated maternal uric acid, increase fetal growth monitoring frequency 4
• For absent end-diastolic flow in umbilical artery before 34 weeks: daily cardiotocograph monitoring, twice weekly umbilical artery Doppler, and amniotic fluid volume assessment 4
• For reversed end-diastolic flow before 30 weeks: hospitalization with daily cardiotocograph monitoring and 3× weekly Doppler studies 4

Timing of Delivery

Gestational Hypertension Without Preeclampsia

• Delivery can be delayed until 39+6 weeks if BP remains controlled, fetal monitoring is reassuring, and preeclampsia has not developed 4, 1, 2

Preeclampsia

• Delivery at term (≥37 weeks) is recommended 1
• Earlier delivery indicated for maternal or fetal compromise 4

Severe Fetal Growth Restriction

• With absent end-diastolic flow: consider delivery no later than 34 weeks 4
• With reversed end-diastolic flow: consider delivery no later than 30 weeks 4

Preeclampsia-Specific Management

Magnesium Sulfate

• Administer for seizure prophylaxis in preeclampsia and for treatment of eclampsia 1, 2
• Indicated for women with proteinuria and severe hypertension, or hypertension with neurological signs 3
• Do not administer with calcium channel blockers due to severe hypotension risk 2

Corticosteroids

• Administer prenatal corticosteroids for fetal lung maturation between 24+0 and 34+0 weeks if delivery likely within 7 days 4, 1
• May be given up to 38+0 weeks for elective cesarean section 4
• Multiple courses not recommended 4

Neuroprotection

• Administer MgSO4 for fetal neuroprotection if delivery planned before 32 weeks 4

Prevention Strategies

• Low-dose aspirin (75-100 mg/day) at bedtime for women with history of early-onset preeclampsia, starting pre-pregnancy or before 16 weeks gestation, continued until delivery 3
• Calcium supplementation ≥1 g daily almost halved preeclampsia risk, with greatest effect in high-risk women 4, 3

Postpartum Management

• Record BP shortly after birth and again within 6 hours 1
• Continue antihypertensive treatment to maintain BP <140/90 mmHg 1
• Switch from methyldopa to alternative agent due to postnatal depression risk 2, 3
• BP typically rises over first 5 postpartum days; women may become hypertensive again after initial normalization 2

Long-Term Cardiovascular Risk and Follow-Up

Women with gestational hypertension or preeclampsia have significantly increased lifetime cardiovascular risk, with relative risk of ischemic heart disease more than doubled. 2, 3

• Recommend annual medical review lifelong for cardiovascular risk assessment 1, 2, 3
• Implement lifestyle modifications and regular BP control to reduce future cardiovascular risk 2, 3
• Control metabolic factors (diabetes, hyperlipidemia, obesity) 2, 3
• Women with early-onset preeclampsia, stillbirth, or fetal growth retardation are at highest risk 2
• Earlier onset in first pregnancy correlates with greater recurrence risk in subsequent pregnancies 2

Common Pitfalls to Avoid

• Do not combine labetalol with calcium channel blockers due to severe hypotension risk 2, 7
• Do not combine magnesium sulfate with calcium channel blockers for the same reason 2
• Do not restrict salt intake, particularly close to delivery, as this may induce low intravascular volume 4
• Do not use atenolol in early pregnancy; if beta-blocker needed, use labetalol or metoprolol 4, 6
• Recognize that BP may appear normal in early pregnancy due to physiological fall, masking pre-existing hypertension 4
• When measuring urinary catecholamines in women on methyldopa, use high-performance liquid chromatography to avoid false-positive results 5