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 (or ≥135/85 mmHg at home), targeting diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1, 2, 3

Blood Pressure Thresholds and Treatment Strategy

Start pharmacological treatment at BP ≥140/90 mmHg for all hypertensive disorders of pregnancy, including chronic hypertension, gestational hypertension, and preeclampsia. 1, 2 This recommendation is based on the CHIPS trial, which demonstrated that tighter BP control reduces severe hypertension without compromising fetal outcomes. 4 The 2018 ISSHP guidelines emphasize that waiting until BP reaches 160/110 mmHg before treating is "logically inconsistent" and increases maternal risk. 4

• Target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg during treatment 1, 3
• Reduce or cease antihypertensives if diastolic BP falls below 80 mmHg to avoid compromising uteroplacental perfusion 2
• Home BP monitoring threshold is ≥135/85 mmHg for treatment decisions 3

Severe Hypertension: Emergency Management

BP ≥160/110 mmHg constitutes a hypertensive emergency requiring immediate hospitalization and treatment within 15 minutes to prevent maternal stroke. 1, 3, 5 This threshold represents a critical point where cerebrovascular complications become significantly more likely. 4

Acute Treatment Options:

• Oral immediate-release nifedipine is first-line for acute management 1, 3
• Intravenous labetalol is equally effective 1, 3, 5
• Intravenous hydralazine is an alternative option 1, 5
• Goal BP: systolic 140-150 mmHg and diastolic 90-100 mmHg within 30-60 minutes 5

First-Line Antihypertensive Medications

Methyldopa, labetalol, and long-acting nifedipine are the three preferred agents for chronic BP control during pregnancy, with established safety profiles and long-term infant follow-up data. 1, 2, 3, 6

Medication-Specific Considerations:

• Methyldopa: Drug of choice based on 7.5-year infant follow-up data, but must be switched postpartum due to postnatal depression risk 4, 3
• Labetalol: Comparable efficacy to methyldopa; do not use concomitantly with calcium channel blockers due to severe hypotension risk 2, 3
• Long-acting nifedipine: Effective for chronic control; immediate-release formulation preferred for acute severe hypertension 2, 3
• Metoprolol: Recommended alternative beta-blocker 4

Absolutely Contraindicated Medications:

ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated due to severe fetotoxicity, particularly in second and third trimesters. 4 If taken inadvertently in first trimester, switch immediately and perform close fetal ultrasound monitoring. 4

Classification and Diagnostic Framework

Understanding the specific type of hypertensive disorder guides management intensity:

Chronic Hypertension:

• Defined as BP ≥140/90 mmHg present before pregnancy or diagnosed before 20 weeks gestation 4, 3
• Complicates 1-5% of pregnancies 4
• May appear normotensive in early pregnancy due to physiological BP fall in first trimester, masking pre-existing hypertension 4, 3
• Requires baseline laboratory assessment including renal function, proteinuria, and metabolic panel 1

Gestational Hypertension:

• New-onset hypertension at or after 20 weeks without proteinuria 4, 3
• Complicates 6-7% of pregnancies 4
• 25% will progress to preeclampsia, requiring vigilant monitoring 1, 2

Preeclampsia:

• Gestational hypertension with proteinuria ≥0.3 g/day (or ≥30 mg/mmol protein/creatinine ratio) 4, 2
• BP level alone is not a reliable risk stratifier - some women develop serious organ dysfunction at relatively mild BP levels 4

Superimposed Preeclampsia:

• Chronic hypertension with new-onset proteinuria or worsening BP after 20 weeks 4, 2
• Protein excretion ≥3 g/day in 24-hour collection defines this category 4

Indications for Immediate Hospitalization

Admit to hospital for any of the following:

• BP ≥160/110 mmHg (severe hypertension) 1, 3
• Development of preeclampsia features (proteinuria, end-organ dysfunction) 1, 2
• Neurological signs or symptoms (severe headache, visual disturbances, hyperreflexia with clonus) 4, 1, 3
• Inability to control BP with ≥3 antihypertensive drug classes 1, 3
• Maternal pulse oximetry <90% 4
• Progressive deterioration in liver function, creatinine, hemolysis, or platelet count 4
• Placental abruption 4
• Reversed end-diastolic flow on umbilical artery Doppler or nonreassuring fetal monitoring 4

Preeclampsia-Specific Management

Magnesium Sulfate for Seizure Prophylaxis:

Administer MgSO4 for seizure prophylaxis in preeclampsia and for treatment of eclampsia. 1, 2, 3 MgSO4 approximately halves the eclampsia rate, with 100 women needing treatment to prevent 1 seizure. 4

Indications for MgSO4:

• Severe hypertension with ≥3+ proteinuria 4
• BP ≥150/100 mmHg with ≥2+ proteinuria plus ≥2 signs of imminent eclampsia (headache, visual symptoms, clonus) 4
• All preeclamptic women in low-resource settings where cost-benefit is greatest 4

Critical Safety Warning: Do not administer MgSO4 with calcium channel blockers due to severe hypotension risk. 3

Timing of Delivery:

• Preeclampsia at term (≥37 weeks): recommend delivery 1, 3
• Preterm preeclampsia with adverse conditions: deliver regardless of gestational age if visual disturbances, coagulation abnormalities, progressive thrombocytopenia, progressively abnormal renal/liver enzymes, pulmonary edema, or fetal distress develop 2, 3
• Antenatal corticosteroids between 24+0 and 34+0 weeks if delivery likely within 7 days for fetal lung maturation 1, 3

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, 3

Non-Pharmacological Management

For BP 140-150/90-99 mmHg without preeclampsia features, consider initial non-pharmacological management:

• Close supervision with frequent BP monitoring 4
• Limitation of activities and some bed rest in left lateral position 4
• Normal diet without salt restriction, particularly close to delivery, as salt restriction may induce low intravascular volume 4
• Short-term hospital stay may be required for confirming diagnosis and ruling out preeclampsia 4

Prevention Strategies

Aspirin Prophylaxis:

Low-dose aspirin (75-150 mg/day) at bedtime starting at 12-16 weeks gestation for women at increased risk of preeclampsia, particularly those with history of early-onset (<28 weeks) preeclampsia. 4, 2, 3 Continue until delivery. 4, 3

Calcium Supplementation:

Calcium supplementation (≥1 g daily, up to 1.2-2.5 g/day) almost halves preeclampsia risk without causing harm, with greatest effect in high-risk women and those with low dietary calcium intake (<600 mg/day). 4, 2, 3

Exercise:

Encourage regular exercise during pregnancy to maintain health, appropriate body weight, and reduce likelihood of hypertension. 2

Weight reduction is not recommended during pregnancy in obese women as it can lead to reduced neonatal weight and slower subsequent growth. 4

Postpartum Management

Record BP shortly after birth and again within 6 hours, continuing antihypertensive treatment as needed to maintain BP <140/90 mmHg. 1

Key postpartum considerations:

• 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 3
• Women with preeclampsia should be considered high-risk for at least 3 days postpartum and monitored closely 2
• Avoid NSAIDs for postpartum analgesia unless other analgesics are ineffective, as they can worsen hypertension 2

Long-Term Cardiovascular Risk

Women with gestational hypertension or preeclampsia have significantly increased lifetime cardiovascular risk, with relative risk of ischemic heart disease more than doubled. 1, 2, 3, 7

Recommend annual medical review lifelong for cardiovascular risk assessment, including: 1, 2, 3

• Achieving prepregnancy weight by 12 months 2
• Limiting interpregnancy weight gain 2
• Regular BP monitoring 2, 7
• Adopting healthy lifestyle with control of metabolic factors 2, 3, 7

Women with early-onset preeclampsia, stillbirth, or fetal growth restriction are at highest risk for future cardiovascular disease. 3

Common Pitfalls to Avoid

• Do not wait until BP reaches 160/110 mmHg to initiate treatment - this increases maternal stroke risk and adverse outcomes 4, 1
• Do not use ACE inhibitors, ARBs, or direct renin inhibitors at any point during pregnancy 4
• Do not combine labetalol with calcium channel blockers due to severe hypotension risk 2, 3
• Do not administer MgSO4 with calcium channel blockers due to severe hypotension risk 3
• Do not assume early pregnancy normotension rules out chronic hypertension - physiological BP fall can mask pre-existing disease 4, 3
• Do not rely solely on BP level to stratify preeclampsia risk - organ dysfunction can occur at relatively mild BP elevations 4