Chronic Hypertension in Pregnancy

Evidence-Based Management for MFM Providers
ACOG Practice Bulletin No. 203 (2019)
ACOG Practice Advisory (April 2022)
SMFM Statement (2022)
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Definition

Hypertension diagnosed before pregnancy or before 20 weeks of gestation
Blood pressure threshold:
≥140/90 mmHg
Hypertension diagnosed for first time during pregnancy that does not resolve postpartum also classified as chronic hypertension
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Epidemiology

Prevalence

0.9-1.5%

of all pregnancies

Trend

↑67%

from 2000 to 2009

Increasing prevalence driven by obesity epidemic and advancing maternal age
ACOG Practice Bulletin No. 203, 2019
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Adverse Maternal Outcomes

Primary Mediator
Superimposed Preeclampsia
Cardiovascular
Malignant HTN
Cerebrovascular accident
Cardiac decompensation
Renal
Acute kidney injury
Renal insufficiency
Renal failure
Severity and duration of hypertension plus organ involvement determine risk magnitude
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Adverse Perinatal Outcomes

Outcome Clinical Significance
Preterm Birth Substantially increased vs normotensive pregnancies
Fetal Growth Restriction Associated with reduced uteroplacental perfusion
Placental Abruption Increased risk with severe/uncontrolled HTN
Perinatal Mortality Elevated risk, especially with superimposed preeclampsia
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CHAP Trial (2022)

Landmark Multicenter RCT

2,408 patients with singleton gestation and mild chronic HTN (BP <160/110)

Intervention: Antihypertensive therapy at ≥140/90 mmHg

Control: No treatment unless BP ≥160/105 mmHg

Primary outcome reduced from 37% to 30.2%
(Adjusted RR 0.82; 95% CI 0.74-0.92)
Tita et al. N Engl J Med 2022; 386:1781-1792
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CHAP Trial: Primary Outcome

Composite Primary Outcome Components

  • Preeclampsia with severe features
  • Medically indicated preterm birth <35 weeks
  • Placental abruption
  • Fetal or neonatal death
Number needed to treat: 14.7
to prevent one adverse outcome
Birthweight <10th percentile similar between groups (no increased FGR with treatment)
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Current Treatment Recommendations

ACOG Practice Advisory (April 2022)

Utilize 140/90 mmHg as threshold for initiation or titration of antihypertensive therapy

SMFM Statement (2022)

Treatment goal: BP <140/90 mmHg

Previous threshold of 160/110 mmHg is no longer recommended
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Preconception & Baseline Assessment

History & Physical

  • Age of onset
  • Previous evaluation results
  • Severity and duration
  • End-organ involvement

Baseline Laboratory

  • Serum creatinine, BUN
  • Urine protein-to-creatinine ratio
  • CBC, platelet count
  • Liver function tests
Ideally evaluate before pregnancy to identify reversible causes and assess organ damage
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Extended Evaluation

Clinical Indication Additional Testing
Longstanding HTN (several years) ECG, echocardiography, ophthalmologic exam, renal ultrasound
Paroxysmal HTN, "crises", anxiety attacks 24-hour urine metanephrines or unconjugated catecholamines (pheochromocytoma screen)
Type 2 diabetes with HTN Doppler flow studies or MRA for renal artery stenosis
Severe HTN on ≥2 medications, hypokalemia Secondary hypertension workup
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First-Line Antihypertensives

Labetalol

200-800 mg BID-TID

Contraindications: asthma, heart disease, CHF

Nifedipine XL

30-60 mg daily

Calcium channel blocker

Methyldopa

250-1000 mg BID-TID

Watch for supply shortages

ACE inhibitors and ARBs are CONTRAINDICATED
Risk of fetal/neonatal renal failure
Switch from ACE-I/ARB prior to conception or with viable pregnancy confirmation
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Preeclampsia Prevention

Low-Dose Aspirin Prophylaxis

81 mg daily

1 Initiate between 12-28 weeks gestation
2 Optimal timing: before 16 weeks
3 Continue until delivery
ACOG Committee Opinion No. 743, Low-Dose Aspirin Use During Pregnancy
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Medication Management in Pregnancy

Already on Medications

Continue established therapy or switch to pregnancy-compatible regimen

Do NOT discontinue and wait for severe range

New Diagnosis in Pregnancy

Initiate therapy at BP ≥140/90 mmHg

Regardless of complicating factors

Goal: BP <140/90 mmHg (not a lower threshold established for FGR risk)
Monitor for medication side effects: dizziness, fatigue, orthostatic hypotension
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Chronic HTN vs Superimposed Preeclampsia

Distinction can be challenging in third trimester when physiologic BP changes occur
Laboratory Test Clinical Application
Serum Creatinine Compare to baseline from early pregnancy
Liver Function Tests Assess for HELLP syndrome features
Platelet Count Monitor for thrombocytopenia
Hematocrit Evaluate for hemoconcentration
Proteinuria Assessment New or worsening proteinuria vs baseline
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Antepartum Surveillance

Maternal Monitoring

  • BP at every prenatal visit
  • Home BP monitoring as indicated
  • Serial laboratory assessment
  • Symptoms review (headache, visual changes, epigastric pain)

Fetal Surveillance

  • Serial growth ultrasounds (third trimester)
  • Antenatal testing starting at 32 weeks
  • Earlier if complications develop
No consensus on optimal test type or interval—individualize based on severity
ACOG Committee Opinion No. 828, Indications for Outpatient Antenatal Fetal Surveillance
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Timing of Delivery

Clinical Scenario Recommended Delivery Timing
Controlled without medications 38.0-39.6 weeks
Controlled with medications 37.0-39.6 weeks
Uncontrolled on medications 36.0-37.6 weeks
Superimposed preeclampsia with severe features Individualized based on gestational age and maternal/fetal status
Delivery prior to 37 weeks should be avoided in absence of complications
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Intrapartum Considerations

1 Continuous fetal monitoring throughout labor
2 Maintain antihypertensive therapy during labor
3 Monitor for severe-range BP (≥160/110 mmHg)
4 Treat severe hypertension urgently (within 30-60 minutes)
Nulliparous patients with chronic HTN may have longer first stage of labor
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Acute Treatment: Severe HTN

Severe Hypertension: SBP ≥160 or DBP ≥110 mmHg
Labetalol IV

20 mg initial

Then 40-80 mg q10min

Max: 220 mg total

Hydralazine IV

5-10 mg initial

Then 10 mg q20min

Max: 30 mg total

Nifedipine PO

10-20 mg immediate release

Repeat in 20 min PRN

Max: 50 mg/hour

Goal: BP <160/110 mmHg within 30-60 minutes
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Postpartum Management

Blood pressure often increases in weeks after delivery
1 Continue home BP monitoring for 1-2 weeks postpartum
2 Follow-up within 72 hours if severe HTN during hospitalization
3 Resume or adjust antihypertensive medications as needed
4 Ensure medications are compatible with breastfeeding
Do not discontinue medications without provider consultation
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Long-Term Cardiovascular Risk

Chronic HTN in pregnancy associated with heightened risk of future cardiovascular disease

Increased Risk For

  • Persistent hypertension
  • Ischemic heart disease
  • Heart failure
  • Stroke

Postpartum Care

  • Cardiovascular risk assessment
  • Lifestyle modification counseling
  • Long-term BP management
  • Regular primary care follow-up
Countouris et al. Circulation 2025; 151:490-507
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Key Clinical Takeaways

1 Treat chronic HTN at ≥140/90 mmHg threshold based on CHAP trial
2 First-line agents: labetalol, nifedipine, methyldopa
3 Initiate aspirin 81 mg daily between 12-28 weeks (ideally <16 weeks)
4 Antenatal testing from 32 weeks; serial growth ultrasounds
5 Deliver at 37-39.6 weeks based on control status
6 Close postpartum monitoring for BP exacerbation
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Key References

1. ACOG Practice Bulletin No. 203: Chronic Hypertension in Pregnancy. Obstet Gynecol 2019;133:e26-50.

2. ACOG Practice Advisory: Clinical Guidance for the Integration of the Findings of the Chronic Hypertension and Pregnancy (CHAP) Study. April 2022.

3. SMFM Statement: Antihypertensive therapy for mild chronic hypertension in pregnancy—The Chronic Hypertension and Pregnancy trial. Am J Obstet Gynecol 2022;227:B24-B27.

4. Tita AT, Szychowski JM, Boggess K, et al. Treatment for Mild Chronic Hypertension during Pregnancy. N Engl J Med 2022;386:1781-1792.

5. ACOG Committee Opinion No. 828: Indications for Outpatient Antenatal Fetal Surveillance. Obstet Gynecol 2021;137:e177-e197.

6. Countouris M, et al. Hypertension in Pregnancy and Postpartum: Current Standards and Opportunities to Improve Care. Circulation 2025;151:490-507.

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