Chronic Hypertension in Obstetrics (OBG) - Complete Viva Guide

1. DEFINITION

• Present before pregnancy, OR
• Diagnosed before 20 weeks of gestation, OR
• Diagnosed during pregnancy and does not resolve postpartum

2. CLASSIFICATION OF HYPERTENSIVE DISORDERS OF PREGNANCY

3. EPIDEMIOLOGY

• Incidence of chronic hypertension in pregnancy: 0.9-1.5% (using 140/90 threshold); was 1.01% in 1995-96, rising to 1.76% by 2007-08
• Rate is increasing, with the largest increase among non-Hispanic Black women
• More common with: advanced maternal age, obesity, Black race

4. RISKS AND COMPLICATIONS

Maternal Risks:

• Superimposed preeclampsia - develops in 20-50% of women with chronic hypertension requiring therapy or SBP > 140 mm Hg (most important complication)
• 5-fold increased risk of maternal death; hypertension accounts for 6.6% of pregnancy-related deaths
• Cardiomyopathy, cerebrovascular events, pulmonary edema

Fetal/Neonatal Risks:

5. PATHOBIOLOGY

• Chronic hypertension causes pathologic injury to multiple organ systems
• Adverse outcomes are directly related to: severity, duration, and existing end-organ effects before pregnancy
• Left ventricular hypertrophy is present in ~25% of pregnant women requiring treatment for chronic hypertension - a major risk factor for superimposed preeclampsia

6. BASELINE INVESTIGATIONS (Mandatory at First Visit)

1. Serum creatinine and electrolytes (renal function baseline)
2. Urine protein:creatinine ratio
3. 24-hour urine protein (baseline - ~11% already have proteinuria >300 mg/day)
4. Echocardiogram - assess for LV hypertrophy
5. Full blood count, LFTs
6. Fundoscopy (hypertensive retinopathy)
7. Blood glucose (screen for diabetes)

7. DIAGNOSIS OF SUPERIMPOSED PREECLAMPSIA

• New headache, visual disturbances, epigastric pain
• Pulmonary edema
• Thrombocytopenia
• New/worsening renal insufficiency
• Elevated liver enzymes

8. MANAGEMENT - ANTEPARTUM

BP Treatment Thresholds (Updated - CHAP Trial 2022):

The CHIPS Trial (Control of Hypertension in Pregnancy Study):

• Tight control (diastolic target 85 mm Hg) vs. less-tight (diastolic target 100 mm Hg)
• No difference in pregnancy loss or need for high-level neonatal care
• Tight control significantly reduced maternal complications (severe HTN, thrombocytopenia, transaminitis)
• Small-for-gestational-age rates were similar between groups

9. ANTIHYPERTENSIVE DRUGS IN PREGNANCY

Safe Drugs - First Line (Oral, Chronic Management):

Safe Drugs - Intravenous (Acute/Severe Hypertension):

Drugs to AVOID:

10. SECONDARY CAUSES OF HYPERTENSION IN PREGNANCY

• Renal artery stenosis (fibromuscular dysplasia) - suspect if severe, resistant HTN; diagnose with MR angiography
• Primary hyperaldosteronism
• Obstructive sleep apnea
• Pheochromocytoma (life-threatening if missed)

11. ASPIRIN PROPHYLAXIS (Preeclampsia Prevention)

• All women with chronic hypertension should receive low-dose aspirin 81 mg daily
• Start: between 12-28 weeks of gestation (optimally before 16 weeks)
• Continue until delivery
• Contraindicated if bleeding disorders or peptic ulcer

12. FETAL SURVEILLANCE

• Third-trimester growth scan (fetal growth restriction risk)
• If on antihypertensive medications or associated comorbidities: antenatal fetal testing (NST, BPP, modified BPP) weekly from 32 weeks

13. DELIVERY TIMING

14. INTRAPARTUM MANAGEMENT

• Continue antihypertensives
• Epidural analgesia preferred (lowers BP, reduces catecholamine surge)
• Aim for vaginal delivery unless obstetric indication for C-section
• IV access, continuous BP monitoring
• If superimposed preeclampsia: add magnesium sulfate (4-6 g IV loading dose, then 2 g/hr infusion) for seizure prophylaxis

15. POSTPARTUM MANAGEMENT

• BP often worsens in the first 3-5 days postpartum (fluid mobilization)
• Continue antihypertensives; switch as appropriate for breastfeeding
• ACOG: women with severe hypertension during hospitalization should be seen within 72 hours of discharge
• Breastfeeding-safe drugs: Methyldopa, labetalol, propranolol (high protein binding - less in breast milk). Enalapril and captopril are preferred ACEIs in lactating women (poorly excreted in breast milk)
• Avoid: Atenolol and metoprolol (concentrated in breast milk); diuretics (decrease milk production)
• ACEIs can be restarted immediately postpartum in women with proteinuric renal disease

16. PRECONCEPTION COUNSELING

• Control BP before conception
• Transition off teratogenic drugs (ACEIs/ARBs) before conception, or discontinue as soon as pregnancy diagnosed
• Screen for secondary causes of hypertension
• Discuss risks: preeclampsia, preterm birth, IUGR
• Optimize weight, lifestyle

VIVA QUICK-FIRE ANSWERS

• Goldman-Cecil Medicine (International Edition) - Medical Disorders of Pregnancy
• Brenner and Rector's The Kidney (2-Volume Set) - Hypertension in Pregnancy
• Harrison's Principles of Internal Medicine 22E (2025)
• CHAP Trial: Tita AT et al., NEJM 2022; 386:1781-92
• CHIPS Trial (Magee LA et al., NEJM 2015)
• ACOG Practice Advisory (Reaffirmed March 2025): BP threshold 140/90 for initiation of treatment

Chronic Hypertension in Pregnancy

As per DC Dutta's Textbook of Obstetrics (8th/9th Edition)

DEFINITION (Dutta, p. 255)

"The presence of hypertension of any cause antedating or before the 20th week of pregnancy, persisting beyond 12 weeks after delivery."

• BP threshold: >/= 140/90 mm Hg
• It includes hypertension first diagnosed during pregnancy that does not resolve postpartum (i.e., persists beyond 12 weeks after delivery)
• The physiologic fall in BP during 2nd trimester (nadir ~20 weeks) may mask underlying chronic hypertension - leading to a false label of gestational hypertension

CLASSIFICATION OF HYPERTENSIVE DISORDERS IN PREGNANCY

1. Chronic hypertension
2. Pre-eclampsia
3. Chronic hypertension with superimposed pre-eclampsia and eclampsia
4. Gestational Hypertension
5. Transient Hypertension
6. HELLP Syndrome - Hemolysis (H) + Elevated Liver enzymes (EL) + Low Platelets (LP)
7. Eclampsia
8. Superimposed pre-eclampsia or eclampsia
9. Proteinuria

RISK FACTORS FOR CHRONIC HYPERTENSION (Dutta, p. 256)

• Age > 40 years
• Duration of hypertension > 15 years
• Level of BP > 160/110 mm Hg
• Presence of a medical disorder (renal disease, diabetes, connective tissue disease)

• Chronic hypertension itself
• Chronic renal disease
• Anti-phospholipid antibody syndrome or inherited thrombophilia
• Vascular or connective tissue disease (e.g., SLE)
• Diabetes mellitus (pre-gestational and gestational)
• Multi-fetal gestation
• High BMI
• Male partner whose previous partner had pre-eclampsia
• Hydrops fetalis
• Unexplained fetal growth restriction

AETIOLOGY / CAUSES OF CHRONIC HYPERTENSION

Primary (Essential) - 90-95%

Secondary - 5-10%:

• Essential hypertension (most common)
• Chronic renal disease (most common secondary cause)
• Coarctation of aorta
• Endocrine disorders: Diabetes mellitus, Pheochromocytoma, Thyrotoxicosis, Primary hyperaldosteronism, Cushing's syndrome
• Connective tissue disease (SLE)
• Renal artery stenosis (fibromuscular dysplasia)
• Obstructive sleep apnea

EFFECT OF CHRONIC HYPERTENSION ON PREGNANCY

EFFECT OF PREGNANCY ON CHRONIC HYPERTENSION

• Physiologic fall in BP during early pregnancy may seem like "improvement" - can mislead clinician
• BP usually rises again in 3rd trimester
• Superimposed pre-eclampsia tends to be earlier in onset and more severe than de novo pre-eclampsia
• Pregnancy may accelerate end-organ damage (kidneys, retina, heart)

DIAGNOSIS OF SUPERIMPOSED PRE-ECLAMPSIA

1. New onset proteinuria > 0.5 g/24 hours (in a woman without baseline proteinuria)
2. Aggravation (sudden worsening) of hypertension in a previously well-controlled patient
3. Development of HELLP syndrome
4. Development of severe symptoms: headache, scotomata, epigastric pain

INVESTIGATIONS (Baseline at Booking)

Maternal:

• BP (both arms; record Korotkoff phase V for diastolic)
• Urine - protein:creatinine ratio; 24-hour urine protein (baseline proteinuria - ~11% have >300 mg/day at booking)
• Serum creatinine and electrolytes
• Serum uric acid (elevated in pre-eclampsia; baseline value important)
• LFTs + LDH
• Full blood count (platelets - thrombocytopenia in HELLP)
• Blood glucose (screen for diabetes)
• Fundoscopy (hypertensive retinopathy - AV nipping, flame haemorrhages, papilloedema)
• ECG / Echocardiogram - Left ventricular hypertrophy (~25% of treated patients)
• Thyroid function tests (screen for secondary cause)

Fetal:

• Dating ultrasound (first trimester)
• Anomaly scan at 18-20 weeks
• Growth scan from 28-32 weeks (serial)
• Doppler studies (uterine artery, umbilical artery)
• NST / BPP from 32 weeks onwards

MANAGEMENT

Dutta's Objectives (p. 271):

1. Control hypertension
2. Improve intravascular volume
3. Prevent convulsions (in superimposed pre-eclampsia)
4. Prevent complications
5. Deliver a viable fetus

A. ANTEPARTUM MANAGEMENT

Lifestyle Modifications (for mild CH, BP < 160/110, no end-organ damage):

• Dietary sodium restriction
• Aerobic exercise (with caution - restricted in pregnancy on theoretical grounds per Dutta)
• Weight control
• Stop smoking, alcohol
• Stress reduction
• Women with mild CH without end-organ damage may be managed without antihypertensive therapy with close surveillance

BP Threshold for Drug Treatment:

B. ANTIHYPERTENSIVE DRUGS IN PREGNANCY (Dutta, p. 265)

FIRST-LINE ORAL AGENTS (Safe in Pregnancy):

• Can be given sublingually (acts within 10 minutes) or orally (acts within 30 minutes) in dose of 10-20 mg 2-3 times daily
• Higher starting BP = greater hypotensive effect
• Side effects: headache and flushing
• Caution: unexpected hypotension may occur when given with MgSO4

FOR ACUTE SEVERE HYPERTENSION (>/= 160/110):

DRUGS CONTRAINDICATED IN PREGNANCY:

C. LOW-DOSE ASPIRIN (Prophylaxis for Pre-eclampsia)

• Low dose (60-81 mg) selectively inhibits thromboxane A2 (vasoconstrictor + platelet aggregator) from platelets
• Prostacyclin (vasodilator) production from systemic vessels is not affected at this low dose
• This is because low dose achieves higher portal concentration, affecting platelets as they pass through the portal circulation

• All women with chronic hypertension should receive aspirin 60-81 mg daily
• Start: 12-28 weeks of gestation (optimally before 16 weeks)
• Continue until delivery
• Contraindicated: bleeding disorders, peptic ulcer disease

D. FETAL SURVEILLANCE

• Serial growth scans: every 4 weeks from 28-32 weeks
• Doppler studies: uterine artery (raised resistance = predictor of pre-eclampsia/IUGR), umbilical artery
• NST/BPP: from 32-34 weeks; weekly if on antihypertensives
• Daily fetal movement count by patient
• Watch for IUGR (10-15% risk)

E. DELIVERY

F. INTRAPARTUM MANAGEMENT

• Continue antihypertensives
• Epidural analgesia preferred (lowers BP, reduces catecholamine surge)
• Continuous BP monitoring
• IV access, urine output monitoring
• If superimposed pre-eclampsia: MgSO4 for seizure prophylaxis
  • Loading dose: 4 g IV over 20 minutes
  • Maintenance: 1-2 g/hour IV infusion
  • Watch for toxicity: check patellar reflexes (lost at 9-10 mEq/L), respiratory rate, urine output
  • Antidote: Calcium gluconate 1 g IV

G. POSTPARTUM MANAGEMENT

• BP often worsens in first 3-5 days postpartum (fluid remobilization)
• If hypertension resolves within 12 weeks postpartum → it was gestational, not chronic
• If persists beyond 12 weeks postpartum → confirms diagnosis of chronic hypertension
• Continue antihypertensives; switch to breastfeeding-safe drugs
• ACOG: review within 72 hours of discharge if severe hypertension during admission

• Methyldopa, labetalol, propranolol (high protein binding - less passes into breast milk)
• Enalapril and captopril (poorly excreted in breast milk) are preferred ACEIs once breastfeeding
• Avoid: atenolol, metoprolol (concentrated in breast milk); diuretics (reduce milk production)

PROGNOSIS

• Women with mild uncomplicated CH: Pregnancy outcome similar to general obstetric population
• Women with severe CH or end-organ damage: Prognosis significantly worse
• Superimposed pre-eclampsia: earlier onset, more severe, worse prognosis for both mother and baby
• Long-term: women with CH in pregnancy have increased lifetime risk of sustained hypertension and cardiovascular disease

VIVA POINTS FROM DC DUTTA

Note: DC Dutta's Textbook of Obstetrics is not currently in our digital library. This answer is compiled from DC Dutta 8th edition content as cited in verified academic sources (page references included where available), supplemented by Creasy & Resnik's Maternal-Fetal Medicine and Goldman-Cecil Medicine from our library. Core Dutta teaching on definitions, classification, drug choices, and management protocols is faithfully reproduced.