Management of Hypertension in Pregnancy

Classification

1. Chronic hypertension — pre-existing hypertension (before 20 weeks or pre-pregnancy)
2. Gestational hypertension — new-onset hypertension ≥20 weeks, without proteinuria, resolving within 3 months postpartum
3. Preeclampsia/eclampsia — new-onset hypertension ≥20 weeks with proteinuria (or end-organ dysfunction)
4. Chronic hypertension with superimposed preeclampsia

Blood Pressure Thresholds and Targets

• Severe hypertension (SBP ≥160 or DBP ≥105 mmHg): antihypertensive therapy is clearly indicated to prevent stroke and cardiovascular complications.
• Mild-to-moderate hypertension: evidence supports treating to a DBP target of 85 mmHg (CHIPS trial). Tight control reduces episodes of severe hypertension without adverse fetal outcomes.
• Avoid BP falling too low — excessive lowering may compromise uteroplacental perfusion.

Antihypertensive Drug Selection

First-Line Oral Agents

First-Line IV Agents (Acute/Severe Hypertension)

• IV Labetalol — good safety data; preferred initial IV agent
• IV Nicardipine — extensive safety data as a tocolytic; effective for acute BP control
• IV Hydralazine — historically used but now second-line IV due to increased risk of maternal hypotension and placental abruption

Second-Line Agents

• Metoprolol — potential once-daily dosing; less safety data than labetalol
• Verapamil / Diltiazem — no adverse fetal effects but limited data
• Clonidine — comparable to methyldopa in mechanism; fewer data

Agents to Avoid or Use Cautiously

Preeclampsia

Diagnosis

• Hypertension ≥140/90 mmHg after 20 weeks plus proteinuria (≥300 mg/24h), or end-organ involvement (thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, new-onset headache/visual disturbance)

Risk Factors

Pathophysiology (key points)

• Impaired trophoblast invasion → high-resistance spiral arteries → placental ischemia
• Excess placental sFlt-1 (soluble VEGF receptor) neutralizes VEGF and PlGF → widespread endothelial dysfunction
• sFlt-1/PlGF ratio: elevated before onset; a low ratio has 99% NPV for ruling out preeclampsia within the next week

Management of Preeclampsia

1. Definitive treatment = delivery (only cure)
2. Antihypertensive therapy as above for BP control
3. Magnesium sulfate for seizure prophylaxis (eclampsia prevention) in severe preeclampsia
4. Monitor for HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets)
5. Fetal surveillance: growth scans, umbilical artery Doppler, fetal well-being monitoring

Delivery Timing

• ≥37 weeks with preeclampsia without severe features: deliver
• ≥34 weeks with severe features or deteriorating maternal/fetal condition: deliver
• <34 weeks with severe features: corticosteroids for fetal lung maturation, then individualize based on maternal/fetal stability

Eclampsia

• Defined as seizures in a woman with preeclampsia
• Management: IV magnesium sulfate (first-line for acute seizure control and prevention of recurrence), BP control, prompt delivery

Chronic Hypertension in Pregnancy

• Screen for secondary causes (renal artery stenosis, primary hyperaldosteronism, OSA, pheochromocytoma) — especially if hypertension is severe or resistant
• Switch to pregnancy-safe antihypertensives before conception where possible; stop ACE inhibitors/ARBs immediately when pregnancy is confirmed
• Counsel about increased risks: superimposed preeclampsia, preterm birth, IUGR
• Follow closely with BP monitoring and urine protein surveillance

Gestational Hypertension

• New-onset hypertension after 20 weeks, without proteinuria, resolving by 12 weeks postpartum
• 15–25% progress to preeclampsia — requires close monitoring
• Associated with increased risk of future hypertension and cardiovascular disease in the mother
• Offspring at increased risk for preterm delivery and IUGR

Non-Pharmacologic Measures

Key Take-Aways