Chronic Hypertension in Pregnancy

See Also

Definitions

Chronic Hypertension in Pregnancy
1. Chronic Hypertension (140/90 mmHg) that extends into pregnancy without Preeclampsia
2. Onset of Hypertension before 20 weeks gestation or persisting beyond 12 weeks after delivery
3. Superimposed Preeclampsia complicates 17 to 25% of chronic Hypertension patients in pregnancy

Risk Factors
Superimposed Preeclampsia Risk Factors in Chronic Hypertension

Age 35 years or higher
Antihypertensive needed for Blood Pressure control
History of prior pregnancy complications
1. Preeclampsia
2. Untrauterine growth retardation
3. Intrauterine Fetal Demise
Comorbid conditions
1. Diabetes Melllitus
2. Systemic Lupus Erythematosus
3. Chronic cardiopulmonary disease
4. Renal disease
Abnormal labs
1. Serum Creatinine >1.0 mg/dl
2. Proteinuria >300 mg/24 hours
3. Phopholipid Antibody positive

Precautions
Chronic Hypertension in Pregnancy

Observe for superimposed Preeclampsia on chronic Hypertension
High index of suspicion if maked Blood Pressure increase or new onset Proteinuria
Chronic Hypertension history for >10 years is a risk for underlying heart disease and cardiovascular complications
1. Cardiomyopathy including cardiomegaly and ventricular hypertrophy
2. Coronary Artery Disease

Labs

Baseline Hypertension labs may be obtained prior to pregnancy or during pregnancy
Standard Hypertension testing
1. Complete Blood Count with Platelet Count
2. Serum Electrolytes including Serum Potassium
3. Serum Creatinine and Blood Urea Nitrogen
4. Spot Urine Protein to Creatinine Ratio (or 24 Hour Urine Protein)
5. Thyroid Stimulating Hormone (if not recently obtained, typically part of Prenatal Labs)
Other labs (consider as baseline when other labs are drawn, given PIH risk)
1. Serum transaminases (AST, ALT)

Diagnostics

Electrocardiogram (EKG) indications
1. Age >30 years
2. Poorly controlled chronic Hypertension >4 years
Echocardiogram
1. Abnormal EKG
2. Cardiopulmonary signs or symptoms
Obsetetric Ultrasound in third trimester
1. Chronic Hypertension is associated with Intrauterine Growth Retardation (IUGR)

Monitoring

Indicated in chronic Hypertension requiring medications
Weekly Fetal Monitoring starting at 32 weeks
1. Estimate amniotic fluid index (AFI) weekly
2. Non-Stress Test (NST) 1-2 times weekly
3. Biophysical Profile (BPP) if NST not reactive
  1. Further evaluation if BPP <8

Management
General

See PIH Blood Pressure Management
See Anti-Hypertensive Medications in Pregnancy
Despite early studies, Aspirin DOES lower Preeclampsia risk and Intrauterine Growth Retardation risk
1. See Preeclampsia Prevention
2. Aspirin 81 mg orally daily starting at 12-28 weeks and continuing until delivery
Hypertension therapy during pregnancy does not reduce pregnancy complications
1. However, persistent Hypertension does have adverse effects on maternal health and is treated as below
2. Evidence supports medication management of mild Chronic Hypertension in Pregnancy
  1. Antihypertensives appropriate for pregnancy are not associated with fetal or maternal pregnancy complications
  2. See Antihypertensives below
3. Low Sodium Diet shows no benefit
4. Minimizing weight gain shows no benefit
5. Exercise restriction offers no benefit
Delivery timing
1. Recommended at 37-39 weeks for those on Antihypertensives (38-39 weeks if not on medications)

Management
Anti-hypertensives

See Blood Pressure Management in Pregnancy
Goal: Lower Systolic Blood Pressure to <140/90
1. New goal as of 2022 (prior goal had been <150-160/100-110 mmHg, much higher than non-pregnant goal)
2. ACOG Practice Advisory
  1. https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2022/04/clinical-guidance-for-the-integration-of-the-findings-of-the-chronic-hypertension-and-pregnancy-chap-study
Anti-hypertensives are now indicated for mild to moderate Chronic Hypertension in Pregnancy
1. Chronic Hypertension and Pregnancy (CHAP) Study found goal <140/90 benefits both mother and fetus
  1. Tita (2022) N Engl J Med 386(19):1781-92 +PMID: 35363951 [PubMed]
2. Original studies found treatment of BP <150/100 did not reduce risk to fetus or prevent Preeclampsia
  1. Antihypertensives benefitted mother only (these do not reduce pregnancy complications)
  2. Based on these findings, only severe chronic Hypertension (>150-160/100-110) was previously treated
  3. References
    1. van Dadelszen (2000) Lancet [PubMed]
    2. (2001) Obstet Gynecol 98(1 suppl): 177-85 [PubMed]
Precautions
1. Aggressive lowering of Blood Pressure may result in adverse fetal outcomes (hypoperfusion)
Antihypertensive used in pregnancy
1. Avoid contraindicated Antihypertensives
  1. Avoid ACE Inhibitors and ARBs (serious fetal risk in second half of pregnancy, mixed data in first trimester)
  2. Avoid Atenolol and Beta Blockers in general (other than Labetalol) due to IUGR risk
  3. Avoid Spironolactone, Eplerenone and Aliskiren
2. Most commonly used Antihypertensives in pregnancy
  1. Labetolol 200 mg orally twice daily (up to 1200 mg twice daily)
  2. Nifedipine XL 30 mg orally twice daily (up to 120 mg daily)
  3. Alpha Methyldopa 500 mg orally twice daily (up to 3000 mg daily in divided doses)
    1. Long safety record, but weak Antihypertensive and less tolerated (Fatigue, Dizziness)
    2. Also, as of 2023, indefinitely unavailable
3. Other Antihypertensives used in pregnancy (less safety data)
  1. Felodipine 5 mg PO daily (up to 20 mg daily)
  2. Hydralazine 10 mg orally three times daily (up to 25 mg three times daily)
  3. Hydrochlorothiazide
    1. Not usually initiated in pregnancy due to volume depletion (esp. in first few weeks of starting)
    2. May be continued if on pre-pregnancy (consult with local expert opinion)

Complications
Pregnancy Related

Superimposed Preeclampsia (17-25% for chronic Hypertension)
Placental Abruption
Intrauterine Growth Retardation

References