What is the recommended management for hypertension in pregnancy?

Management of Hypertension in Pregnancy

Blood Pressure Thresholds for Treatment Initiation

Initiate antihypertensive therapy at BP ≥140/90 mmHg in women with gestational hypertension (with or without proteinuria), pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms at any time during pregnancy. 1

• For all other pregnant women with chronic hypertension without these features, treatment should begin at BP ≥150/95 mmHg 2, 1
• These thresholds apply whether BP is measured in the office (≥140/90 mmHg) or at home (≥135/85 mmHg) 1
• Target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg during treatment 1

A common pitfall is delaying treatment in women with "mild" hypertension who have gestational hypertension or organ involvement—these women require treatment at the lower 140/90 mmHg threshold, not 150/95 mmHg. 2, 1

Severe Hypertension: Emergency Management

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

Acute Treatment Options for Severe Hypertension:

• Oral immediate-release nifedipine is a first-line option for acute management 1
• Intravenous labetalol is equally effective 2, 1, 3
• Intravenous hydralazine is no longer the preferred agent due to more perinatal adverse effects compared to other drugs 2
• For hypertensive crisis: sodium nitroprusside IV at 0.25-5.0 mg/kg/min, though prolonged use risks fetal cyanide poisoning 2
• For pre-eclampsia with pulmonary edema specifically: nitroglycerin IV starting at 5 mg/min, increased every 3-5 minutes to maximum 100 mg/min 2

First-Line Antihypertensive Medications for Ongoing Control

Methyldopa, labetalol, and long-acting nifedipine are the three preferred agents for chronic BP control during pregnancy. 1, 4, 5, 6

Methyldopa:

• Traditional drug of choice with extensive safety data 5, 6
• Avoid postpartum due to risk of postnatal depression 2
• May cause false-positive urine catecholamine levels, interfering with pheochromocytoma diagnosis 7

Labetalol:

• Efficacy comparable to methyldopa 5
• Safe throughout pregnancy 4, 6
• Small amounts (0.004% of maternal dose) excreted in breast milk 3
• Do not use concomitantly with calcium channel blockers (like nifedipine) due to risk of severe hypotension 8

Long-Acting Nifedipine:

• Extensive safety data available 6
• Preferred calcium antagonist 6

Contraindicated Medications:

• ACE inhibitors and angiotensin receptor blockers are absolutely contraindicated due to fetopathy risk 2, 4, 5
• Atenolol should be avoided due to concerns with fetal growth restriction 4
• Direct renin inhibitors are contraindicated 2

Classification and Diagnostic Approach

Chronic Hypertension:

• Hypertension present before pregnancy or diagnosed before 20 weeks gestation 2, 1
• Requires baseline laboratory assessment including renal function and proteinuria 1
• Women should continue current medications except ACE inhibitors, ARBs, and direct renin inhibitors 2

Gestational Hypertension:

• New-onset hypertension at or after 20 weeks without proteinuria 2, 1
• 25% will progress to preeclampsia, requiring close monitoring 1
• Must have documented normal BP before 20 weeks to make this diagnosis 2

Transient Gestational Hypertension:

• Elevated BP in clinic that normalizes with repeated readings over several hours 2
• Carries 40% risk of developing true gestational hypertension or preeclampsia—requires careful follow-up 2

White-Coat Hypertension:

• Elevated clinic BP with normal ambulatory or home readings 2
• Must be present from early pregnancy to distinguish from transient gestational hypertension 2

Indications for Hospitalization

Admit for any of the following: 1

• BP ≥160/110 mmHg (severe hypertension)
• Development of preeclampsia features (proteinuria, headache, visual changes, epigastric pain, elevated liver enzymes, thrombocytopenia)
• Neurological signs or symptoms
• Inability to control BP with ≥3 antihypertensive drug classes

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 1
• Preeclampsia at term (≥37 weeks): recommend delivery 1
• Gestational hypertension with proteinuria plus adverse conditions (visual disturbances, coagulation abnormalities, fetal distress): induction of delivery is indicated 2

Preeclampsia-Specific Management

• Magnesium sulfate for seizure prophylaxis in preeclampsia and for treatment of eclampsia 1, 8
• Do not administer magnesium sulfate with calcium channel blockers due to severe hypotension risk 8
• Antenatal corticosteroids between 24+0 and 34+0 weeks if delivery likely within 7 days 1
• Position patient in left lateral decubitus to relieve vena cava compression 8

Postpartum Management

• Record BP shortly after birth and 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
• BP typically rises over first 5 postpartum days; women may become hypertensive again after initial normalization 2
• If BP remains elevated at 3 months postpartum, diagnose as chronic hypertension 2

Long-Term Cardiovascular Risk

Women with gestational hypertension or preeclampsia have significantly increased lifetime cardiovascular risk: 2, 1, 4, 6

• Nearly 4-fold increased risk of developing chronic hypertension 2
• More than 2-fold increased risk of ischemic heart disease 2
• Increased stroke risk 2
• Highest risk in women with early-onset preeclampsia (delivery before 32 weeks), stillbirth, or fetal growth restriction 2
• Recommend annual medical review lifelong for cardiovascular risk assessment 1