II. Definitions
- Chronic Hypertension in Pregnancy
- Chronic Hypertension (140/90 mmHg) that extends into pregnancy without Preeclampsia
- Onset of Hypertension before 20 weeks gestation or persisting beyond 12 weeks after delivery
- Gestational Hypertension
- Hypertension in Pregnancy with onset beyond 20 weeks gestation and NO Proteinuria
III. Complications: Pregnancy Related
- Superimposed Preeclampsia (20-50% of cases)
- Placental Abruption
- Intrauterine Growth Retardation
IV. Risk Factors: Superimposed Preeclampsia Risk Factors
- Age 35 years or higher
- Antihypertensive needed for Blood Pressure control
- History of prior pregnancy complications
- Preeclampsia
- Untrauterine growth retardation
- Intrauterine Fetal Demise
- Comorbid conditions
- Diabetes Melllitus
- Systemic Lupus Erythematosus
- Chronic cardiopulmonary disease
- Renal disease
- Abnormal labs
- Serum Creatinine >1.0 mg/dl
- Proteinuria >300 mg/24 hours
- Phopholipid Antibody positive
V. Labs
- Baseline Hypertension labs may be obtained prior to pregnancy or during pregnancy
- Standard Hypertension testing
- Complete Blood Count
- Serum Electrolytes
- Serum Creatinine and Blood Urea Nitrogen
- Spot Urine Protein to Creatinine Ratio
- Thyroid Stimulating Hormone (if not recently obtained, typically part of Prenatal Labs)
- Consider baseline Electrocardiogram (EKG)
- Other labs
- Serum transaminases
VI. Monitoring
- Initial evaluation (at time of diagnosis)
- Estimate Fetal Growth
- Estimate amniotic fluid index (AFI)
- Non-Stress Test (NST)
- Biophysical Profile (BPP) if NST not reactive
- Further evaluation if BPP <8
- Repeat Testing
- Ultrasound every 4 weeks starting at 28 weeks gestation
- Other testing as indicated for significant maternal status changes
VII. 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
- See Preeclampsia Prevention
- Aspirin 81 mg orally daily starting at 12-28 weeks and continuing until delivery
-
Hypertension therapy during pregnancy does not reduce pregnancy complications
- However, persistent Hypertension does have adverse effects on maternal health and is treated as below
- Evidence supports medication management of mild Chronic Hypertension in Pregnancy
- Antihypertensives appropriate for pregnancy are not associated with fetal or maternal pregnancy complications
- See Antihypertensives below
- Low Sodium Diet shows no benefit
- Minimizing weight gain shows no benefit
- Exercise restriction offers no benefit
- Delivery timing
- Recommended at 37-39 weeks for those on Antihypertensives (38-39 weeks if not)
VIII. Management: Anti-hypertensives
- See Blood Pressure Management in Pregnancy
- Goal: Lower Systolic Blood Pressure to <140/90
- New goal as of 2022 (prior goal had been <150-160/100-110 mmHg, much higher than non-pregnant goal)
- ACOG Practice Advisory
- Anti-hypertensives are now indicated for mild to moderate Chronic Hypertension in Pregnancy
- Chronic Hypertension and Pregnancy (CHAP) Study found goal <140/90 benefits both mother and fetus
- Original studies found treatment of BP <150/100 did not reduce risk to fetus or prevent Preeclampsia
- Antihypertensives benefitted mother only (these do not reduce pregnancy complications)
- Based on these findings, only severe chronic Hypertension (>150-160/100-110) was previously treated
- References
- Precautions
- Aggressive lowering of Blood Pressure may result in adverse fetal outcomes (hypoperfusion)
-
Antihypertensive used in pregnancy
- Avoid contraindicated Antihypertensives
- Avoid ACE Inhibitors and ARBs (serious fetal risk in second half of pregnancy, mixed data in first trimester)
- Avoid Atenolol and Beta Blockers in general (other than Labetalol) due to IUGR risk
- Avoid Spironolactone, Eplerenone and Aliskiren
- Most commonly used Antihypertensives in pregnancy
- Labetolol 200 mg orally twice daily (up to 1200 mg twice daily)
- Nifedipine XL 30 mg orally twice daily (up to 120 mg daily)
- Alpha Methyldopa 500 mg orally twice daily (up to 3000 mg daily in divided doses)
- Long safety record, but weak Antihypertensive and less tolerated (Fatigue, Dizziness)
- Also, as of 2023, indefinitely unavailable
- Other Antihypertensives used in pregnancy (less safety data)
- Felodipine 5 mg PO daily (up to 20 mg daily)
- Hydralazine 10 mg PO tid (up to 25 mg tid)
- Hydrochlorothiazide
- Not usually initiated in pregnancy due to volume depletion (esp. in first few weeks of starting)
- May be continued if on pre-pregnancy - consult with local expert opinion
- Avoid contraindicated Antihypertensives
IX. 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
X. Precautions: Gestational Hypertension
- Preeclampsia will develop in 50% of those with Gestational Hypertension onset 24-35 weeks
- Severe Gestational Hypertension is associated with worse outcomes than mild PIH
- Treat with same management protocol as Severe Preeclampsia
- Buchbinder (2002) Am J Obstet Gynecol 186:66-71 [PubMed]