Management of Hypertension in Pregnancy: Current Guidelines

1. Classification

2. Blood Pressure Thresholds and Treatment Targets

When to Start Treatment (2024 ESC Guidelines)

• Gestational hypertension: Start drug treatment when confirmed SBP ≥140 mmHg or DBP ≥90 mmHg (Class I, Level B)
• Chronic hypertension in pregnancy: Same threshold - confirmed office SBP ≥140 or DBP ≥90 mmHg (Class I, Level B)
• All other cases (milder risk profile): Start when SBP ≥150 or DBP ≥95 mmHg

Note: The 2013 ACOG Task Force and older practice bulletins recommended a higher threshold (SBP ≥160 or DBP ≥105 mmHg) for chronic hypertension without end-organ damage. However, the CHIPS Trial data showed that "tight" blood pressure control (target DBP 85 mmHg) significantly reduced maternal complications - particularly severe hypertension (27.5% vs 40.6%), thrombocytopenia, and transaminitis - without increasing fetal risk or small-for-gestational-age births. This shifted guideline targets toward tighter control. - Brenner and Rector's The Kidney, p. 2159

Target BP During Treatment

• ESC 2024: Lower BP to <140/90 mmHg, but DBP should not go below 80 mmHg (to preserve uteroplacental perfusion) - Class I, Level C

Severe/Emergency Thresholds

• SBP ≥170 or DBP ≥110 mmHg: Admission to hospital is recommended (ESC 2024, Class I, Level C)
• SBP ≥160 or DBP ≥110 mmHg: Immediate hospitalisation should be considered

3. Choice of Antihypertensive Agents

Drugs to AVOID in Pregnancy

• ACE inhibitors and ARBs - associated with fetal renal agenesis, oligohydramnios, and neonatal renal failure (contraindicated in all trimesters)
• Renin inhibitors (e.g., aliskiren) - similarly contraindicated
• Sodium nitroprusside - risk of fetal cyanide toxicity
• Atenolol - associated with fetal growth restriction; avoid specifically

First-Line Oral Agents for Mild-Moderate Hypertension (BP 140-159/90-109 mmHg)

• Starting dose: 100 mg twice daily
• A 2025 network meta-analysis (Hup et al., AJOG, PMID: 40216176) found labetalol significantly reduced severe hypertension vs placebo (RR 0.20, 95% CI 0.09-0.48). Compared to nifedipine, labetalol was associated with less preeclampsia (RR 0.50) and less preterm birth (RR 0.68)
• The ESC 2024 states most evidence exists for labetalol among beta-blockers

• Starting dose: 30 mg once daily (extended release)
• Generally considered first choice among CCBs per ESC 2024; also felodipine, amlodipine, isradipine may be used
• Evidence: reduces severe hypertension vs placebo (RR 0.44 with methyldopa-equivalent effect); may provide lower BP with fewer neonatal complications than labetalol in severe acute hypertension settings

• Starting dose: 250 mg twice daily
• Longest safety track record in pregnancy; acceptable but the ESC 2024 meta-analysis suggests beta-blockers and CCBs are more effective than methyldopa at preventing severe hypertension
• Rarely used for non-pregnant hypertension but remains a safe option in pregnancy

4. Management of Acute Severe Hypertension (BP ≥160/110 mmHg)

ESC 2024 states IV hydralazine is a second-line option for severe hypertension; may be associated with more perinatal adverse events than labetalol or nifedipine.

5. Seizure Prophylaxis in Preeclampsia

• Magnesium sulphate is the drug of choice for seizure prevention (eclampsia prophylaxis) in severe preeclampsia and for treating eclampsia
• Also recommended postpartum for women with CNS manifestations (headache, visual disturbance, altered consciousness) - approximately 20% of eclampsia episodes occur >48 hours after delivery
• Magnesium has documented efficacy and lacks adverse effects on mother or baby - Goodman & Gilman's, p. 2159

6. Preeclampsia Prevention

• Low-dose aspirin (75-150 mg/day) started at 12-16 weeks gestation is recommended for women at high risk of preeclampsia (prior preeclampsia, chronic hypertension, renal disease, diabetes, multifetal pregnancy, obesity, antiphospholipid syndrome)
• Evidence supports aspirin reducing preeclampsia incidence by approximately 10-15%

7. Delivery Timing

• Severe preeclampsia with mature fetus: Delivery is the definitive treatment
• Severe preeclampsia before 34 weeks: Hospitalisation + pharmacotherapy to allow fetal maturation; corticosteroids for fetal lung maturity
• Gestational hypertension or preeclampsia without severe features: Expectant management with close monitoring until 37 weeks, then delivery

8. Postpartum Considerations

• BP may worsen in the first 24-48 hours postpartum - ACOG recommends follow-up within 72 hours of discharge for women with severe hypertension during hospitalisation
• Continue antihypertensives postpartum as BP often does not normalise immediately
• RAS inhibitors (ACE inhibitors, ARBs) are safe for breastfeeding and can be started postpartum

9. Secondary Causes in Pregnancy

Key Recent Evidence

• Hup et al. 2025 (PMID 40216176) - Network meta-analysis (23 RCTs, 3,989 women): labetalol and methyldopa significantly reduce severe hypertension vs placebo; labetalol shows modest advantage over nifedipine for preeclampsia and preterm birth outcomes. Overall quality of evidence was low-to-moderate.
• CHIPS Trial: Tight BP control (target DBP 85 mmHg) significantly reduces maternal complications vs less-tight control (DBP 100 mmHg), with no increased fetal harm - supporting tighter treatment thresholds.
• 2024 ESC Guidelines (Section 9.2): Updated recommendations to treat chronic and gestational hypertension from ≥140/90 mmHg (not just ≥160/110 mmHg), aligning with CHIPS data.