Management of Hypertension in Pregnancy — Current Guidelines

Comprehensive Clinical Nephrology, 7th Edition, Fig. 44.3

1. Classification

2. Blood Pressure Thresholds for Treatment

Severe Hypertension (SBP ≥ 160 or DBP ≥ 105 mmHg)

Mild-to-Moderate Hypertension (140–159/90–104 mmHg)

• The ACOG Task Force historically recommended against routine antihypertensive use in women with chronic HTN and BP <160/105 mmHg without end-organ damage, citing concerns that aggressive BP lowering may impair fetal growth via reduced uteroplacental perfusion.
• The CHIPS Trial (Control of Hypertension in Pregnancy Study) showed that treating to a tight DBP target of 85 mmHg versus less-tight control (DBP 100 mmHg) was safe — no difference in pregnancy loss or high-level neonatal care — but significantly reduced maternal complications (severe HTN, thrombocytopenia, transaminitis).
• Current guidance therefore supports treating to a target DBP of 85 mmHg in most women to reduce maternal risk without harming the fetus.

The 2025 Circulation review (Countouris et al., PMID 39960983) highlights that national and international guidelines still differ in treatment thresholds and targets, and calls for more trials to establish optimal BP ranges peripartum and postpartum.

3. Safe Antihypertensive Agents in Pregnancy

Contraindicated Agents

• ACE inhibitors (captopril, enalapril) — teratogenic (renal dysgenesis, oligohydramnios, fetal hypocalvaria); contraindicated in all trimesters
• Angiotensin receptor blockers (ARBs) — same fetotoxic profile; contraindicated
• Spironolactone — theoretical risk of inadequate male fetal virilisation; avoid (eplerenone may be used if essential)
• Thiazide diuretics — generally avoided (reduce uteroplacental perfusion); use only if volume overload is a concern

4. Management of Specific Scenarios

Chronic Hypertension

• Control BP before conception using pregnancy-safe agents; switch from unsafe drugs (ACEi, ARB) as soon as pregnancy is confirmed
• Follow closely for superimposed preeclampsia (sudden BP rise in previously well-controlled patient, new proteinuria, thrombocytopenia, elevated liver enzymes, headache, visual changes)
• Screen for secondary causes: primary hyperaldosteronism, renal artery stenosis, phaeochromocytoma, obstructive sleep apnoea (≥40% of pregnant women with HTN have OSA)

Gestational Hypertension

• Monitor BP closely; ~25% will progress to preeclampsia
• Initiate antihypertensives if BP ≥ 140/90 mmHg persists

Preeclampsia — Non-Severe

• Hospitalise or manage with close outpatient surveillance
• Initiate antihypertensives; aim for BP <150/100 mmHg
• Serial fetal assessment (growth scans, umbilical artery Doppler)
• Plan delivery at 37 weeks or earlier if features of severity

Severe Preeclampsia / Eclampsia

• Acute BP control: Labetalol IV (20 mg, escalate to 40 mg at 10 min if insufficient) or Hydralazine IV 5–10 mg q20 min or Nifedipine oral (avoid sublingual)
• Seizure prophylaxis/treatment: Magnesium sulfate IV — documented efficacy for seizure prevention and treatment; no adverse maternal/fetal effects at therapeutic doses; continue for 24 h postpartum. Treat all women with severe preeclampsia or CNS manifestations (headache, visual disturbance, altered consciousness)
• ~20% of eclampsia occurs >48 h postpartum — magnesium coverage must extend into the postpartum period
• Definitive treatment: Delivery — if severe features are present and fetus is sufficiently mature. If preterm, hospitalisation ± corticosteroids for fetal lung maturation and temporising antihypertensive therapy may be used to gain fetal maturity

HELLP Syndrome

• Haemolysis, Elevated Liver enzymes, Low Platelets
• AKI incidence 10–25% in HELLP; urgent delivery indicated when AKI occurs
• Differentiate from TTP (plasmapheresis beneficial in TTP but not HELLP) and AFLP

5. Prevention of Preeclampsia

6. Postpartum Management

• BP may spike in the first 3–5 days postpartum even in women who were normotensive intrapartum
• Methyldopa, labetalol, nifedipine, and enalapril/captopril are compatible with breastfeeding
• ACEi/ARBs can be used postpartum (no longer teratogenic concern)
• All women with HDP should have cardiovascular risk review at 6–12 weeks postpartum — HDP is an independent risk factor for future hypertension, ischaemic heart disease, stroke, and CKD
• Home BP monitoring programs have been shown to improve BP ascertainment across diverse populations and lower BP in the months after delivery

7. Investigations at Diagnosis

• Urine protein:creatinine ratio (PCR) or albumin:creatinine ratio (ACR), 24-h urine protein
• FBC (thrombocytopenia in HELLP/preeclampsia)
• Serum creatinine, LFTs, uric acid
• Coagulation screen if HELLP suspected
• Placental growth factor (PlGF) — a low PlGF or high sFlt-1/PlGF ratio predicts preeclampsia with high accuracy and can be used to rule out preeclampsia in suspected cases
• Fetal ultrasound: growth biometry, umbilical artery Doppler

Key Evidence Updates (2023–2025)

• [PMID 39960983] Countouris et al., Circulation 2025: Reviews current standards and notes that guidelines still differ on treatment thresholds; highlights the value of postpartum HTN clinics and home BP monitoring for long-term cardiovascular risk reduction.
• [PMID 37391211] Wu et al., BMJ 2023: Comprehensive review confirming PlGF-based testing improves identification of high-risk preeclampsia; affirms aspirin prophylaxis and confirms delivery timing evidence for non-severe preeclampsia.
• CHIPS Trial (landmark RCT): Tight DBP target 85 mmHg is safe and reduces maternal complications without increasing fetal harm — supports more aggressive treatment of mild-to-moderate HTN than older guidelines suggested.