Hypertension During Pregnancy: Comprehensive Reporting Outline
I. Classification of Hypertensive Disorders in Pregnancy
Hypertension in pregnancy affects 5-10% of pregnancies worldwide and encompasses five distinct clinical entities that require different management approaches. 1
A. Chronic (Preexisting) Hypertension
- Hypertension present before pregnancy or diagnosed before 20 weeks of gestation 1
- Persists beyond 6 weeks postpartum 1
- Key risks include superimposed preeclampsia (25% risk), fetal growth restriction, and accelerated maternal hypertension 1, 2
- Associated with higher rates of preterm birth, placental abruption, and fetal death 2
B. Gestational Hypertension
- New-onset hypertension appearing after 20 weeks of gestation 1
- Resolves within 6 weeks postpartum 1
- Not a benign disorder: at least 25% of cases progress to preeclampsia 1
- Highest progression risk when diagnosed before 34 weeks 1
C. Preeclampsia
- Hypertension with proteinuria (>300 mg/24h or ACR >30 mg/mmol) 1
- Predisposing factors: preexisting hypertension, previous hypertensive pregnancy, diabetes, renal disease, first or multiple pregnancy 1
- All cases may become emergencies rapidly; avoid attempting to classify as "mild" versus "severe" 1
D. Eclampsia
- Preeclampsia with seizures, severe headaches, visual disturbances, abdominal pain, nausea/vomiting, or low urinary output 1
- Requires immediate treatment and delivery 1
E. HELLP Syndrome
F. Chronic Hypertension with Superimposed Preeclampsia
- Preexisting hypertension with new-onset proteinuria after 20 weeks 1
- Carries worse maternal and fetal outcomes than either condition alone 1
II. Blood Pressure Measurement and Diagnosis
A. Diagnostic Criteria
- Hypertension defined as systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg on two separate occasions 1, 3
- Severe hypertension: ≥160/110 mmHg 1
B. Measurement Techniques
- Use manual auscultatory device or automated upper-arm cuff validated specifically for pregnancy and preeclampsia 1
- Validated devices listed at www.stridebp.org 1
- ABPM or home BP monitoring using pregnancy-validated devices to evaluate white coat hypertension, especially in women with diabetes or nephropathy 1
- Up to 25% of elevated clinic readings represent white coat hypertension 2
III. Preconception Assessment and Optimization
A. Mandatory Preconception Evaluation
- Comprehensive screening for secondary hypertension is mandatory in women diagnosed before age 40 (except obese women where sleep apnea evaluation should be prioritized first) 2
- Assess BP status, severity, possible secondary causes, and target organ damage 1
- Screen for pheochromocytoma due to high morbidity/mortality if undiagnosed 1
B. Baseline Laboratory Assessment
- Complete blood count, liver enzymes, serum creatinine, electrolytes, uric acid 2
- Urinalysis with protein-to-creatinine ratio to establish baseline for detecting superimposed preeclampsia 2
- Assessment for target organ damage: retinopathy, renal disease, ventricular hypertrophy 2
C. Critical Medication Changes
- ACE inhibitors, ARBs, direct renin inhibitors, and mineralocorticoid receptor antagonists are absolutely contraindicated and must be discontinued before conception attempts 1, 2, 4
- These agents cause fetal teratogenicity, oligohydramnios, and fetal death 1, 2
- Transition immediately to pregnancy-safe agents: extended-release nifedipine (preferred first-line), labetalol, or methyldopa 2
IV. Investigation During Pregnancy
A. Initial Workup
- Urine analysis, full blood count, liver enzymes, hematocrit, serum creatinine, and uric acid 1
- Test for proteinuria in early pregnancy (preexisting renal disease) and second half (preeclampsia) 1
- Dipstick >1+ should be followed by UACR in spot urine; UACR <30 mg/mmol excludes proteinuria 1
B. Specialized Testing
- Ultrasound of kidneys and adrenals 1
- Free plasma metanephrines if clinical features of pheochromocytoma 1
- Doppler ultrasound of uterine arteries after 20 weeks to detect higher risk of gestational hypertension, preeclampsia, and intrauterine growth retardation 1
V. Prevention Strategies
A. Aspirin Prophylaxis
- 75-162 mg aspirin daily from weeks 12-36 for women at high or moderate risk 1
- High risk: hypertension in previous pregnancy, CKD, autoimmune disease, diabetes, chronic hypertension 1
- Moderate risk: first pregnancy in woman >40 years, pregnancy interval >10 years, BMI >35 kg/m², family history of preeclampsia, multiple pregnancies 1
- Start at bedtime before 16 weeks gestation 2
B. Calcium Supplementation
- 1.5-2 g/day oral calcium for women with low dietary intake (<600 mg/day) 1
C. Lifestyle Modifications
- Sodium restriction to 2.4 g daily 1, 2
- Low- to moderate-intensity exercise recommended in consultation with obstetrician 2
- Weight reduction should NOT be attempted during pregnancy, even in obese women 1, 2
- Alcohol and tobacco must be strongly discouraged 1
VI. Blood Pressure Targets and Treatment Thresholds
A. Treatment Initiation
- Initiate pharmacological treatment when BP is ≥140/90 mmHg in women with chronic hypertension 1, 2
- Treatment must be reinstituted when BP reaches 150-160/100-110 mmHg to prevent severe elevations 1, 2
- For women at high cardiovascular risk, treatment may be initiated at ≥130/80 mmHg after 3 months of lifestyle intervention 2
B. Target Blood Pressure
- Target diastolic BP of 85 mmHg and systolic BP 110-140 mmHg 1, 2
- Systolic BP should be at least <160 mmHg 1
- Reduce or cease antihypertensive drugs if diastolic BP falls <80 mmHg 1
- Do not lower diastolic BP below 80 mmHg to balance maternal cardiovascular protection with adequate uteroplacental perfusion 1, 2
VII. Pharmacological Management
A. First-Line Agents for Chronic Management
- Extended-release nifedipine: preferred first-line agent with strongest safety data and once-daily dosing 2
- Labetalol: excellent alternative, particularly for women without reactive airway disease 1, 2
- Methyldopa: longest safety record with long-term infant outcome data, but use cautiously in women at risk for depression 1, 2
- Oxprenolol, with second or third-line agents hydralazine and prazosin 1
B. Agents to Avoid
- Atenolol: associated with intrauterine growth retardation 1, 2
- Diuretics: generally avoided due to risk of reducing uteroplacental perfusion 1, 2
- ACE inhibitors, ARBs, direct renin inhibitors, mineralocorticoid receptor antagonists: absolutely contraindicated 1, 2, 4
C. Acute Severe Hypertension (≥160/110 mmHg)
- Requires urgent treatment in a monitored setting regardless of hypertensive disorder type 1
- Acceptable agents: oral nifedipine, intravenous labetalol, or intravenous hydralazine 1
- Aim to maintain BP <170/110 but not lower than 130/90 to prevent maternal cerebrovascular damage while maintaining placental perfusion 5
D. Drug Interactions and Precautions
- Grapefruit juice should be avoided by patients on nifedipine; stop at least 3 days prior to initiating nifedipine 4
- Careful monitoring required when administering nifedipine with IV magnesium sulfate due to risk of excessive BP fall 4
- St. John's Wort decreases nifedipine exposure; consider alternative therapy 4
VIII. Management by Specific Condition
A. Chronic Hypertension
- Control BP to 110-140/85 mmHg 1
- Monitor for superimposed preeclampsia using urinalysis at each visit, clinical assessment, and blood tests (Hb, platelets, liver transaminases, uric acid, creatinine) at minimum 28 and 34 weeks 1
- Assess fetal well-being with ultrasound from 26 weeks, then every 2-4 weeks if normal 1
- Women with target organ damage or prior requirement for multiple agents should continue antihypertensive medication 1
B. Gestational Hypertension
- Control BP to 110-140/85 mmHg 1
- Monitor for development of preeclampsia 1
- Monitor fetal growth, especially if maternal uric acid elevated 1
- Delivery can be delayed until 39+6 weeks provided BP controlled, fetal monitoring reassuring, and preeclampsia has not developed 1
- Optimal delivery timing appears to be 38-39 weeks based on retrospective data 1
C. Preeclampsia Management
- All women should be assessed in hospital when first diagnosed 1
- Some may be managed as outpatients once stable, reliable for reporting problems, and able to monitor BP 1
- Women with proteinuria and severe hypertension, or hypertension with neurological signs/symptoms, should receive MgSO₄ for convulsion prophylaxis 1
- Plasma volume expansion is NOT recommended routinely 1
D. Preeclampsia at ≥37 Weeks
- Immediate delivery recommended regardless of severity 6
- Attempt vaginal delivery if no obstetric contraindications; cesarean section reserved for usual obstetric indications 6
IX. Monitoring Protocols
A. Maternal Monitoring in Preeclampsia
- BP monitoring every 4 hours or more frequently if necessary 6
- Clinical assessment including clonus and deep tendon reflexes 1, 6
- Blood tests (Hb, platelet count, liver transaminases, creatinine, uric acid) at least twice weekly 1, 6
- Repeat assessments for proteinuria if not already present 1
- Blood test evaluation should be performed again in response to any change in clinical status 1
B. Fetal Monitoring in Preeclampsia
- Assessment of fetal biometry, amniotic fluid, and umbilical artery Doppler at first diagnosis 1
- Thereafter at 2-week intervals if initial assessment normal 1
- More frequent amniotic fluid and Doppler assessment in presence of fetal growth restriction 1
C. Monitoring During Labor and Postpartum
- Continuous BP monitoring, cardiotocography, and magnesium sulfate administration during labor and for 24 hours postpartum 6
- Monitor for alarm signs: severe headache, visual disturbances, epigastric pain, dyspnea 6
X. Magnesium Sulfate for Seizure Prophylaxis
A. Indications
- Women with preeclampsia who have proteinuria and severe hypertension 1
- Women with hypertension and neurological signs or symptoms 1
- Women with preeclampsia and symptoms such as headache, even if mild 6
B. Administration
- Loading dose: 4 g IV or 10 g IM 1
- Maintenance: 5 g IM every 4 hours OR 1 g/h infusion 1
- Continue until delivery and for at least 24 hours postpartum 1, 6
- In low-resource settings, all women with preeclampsia should receive MgSO₄ 1
XI. Delivery Timing and Indications
A. Immediate Delivery Required
- Eclampsia 1
- HELLP syndrome 1
- Preeclampsia at ≥37 weeks gestation 6
- Severe hypertension unresponsive to treatment 1
- Maternal or fetal distress 5
B. Expectant Management Considerations
- For significantly premature fetuses (<34 weeks) with severe hypertension, delivery may be deferred after initial stabilization 5
- Requires meticulous monitoring of maternal and fetal state with prompt delivery if deterioration occurs 5
- Antenatal corticosteroids should be given without delaying delivery to complete courses 7
XII. Special Populations
A. Chronic Kidney Disease in Pregnancy
- Maternal and fetal outcomes worse than general population even with mild CKD 1
- Control of maternal BP important to pregnancy and long-term maternal renal outcome 1
- Monitoring for superimposed preeclampsia and adequate fetal growth is critical 1
- Early dialysis with aggressive prescription of approximately 36 hours per week conveys best outcome for progressive renal disease 1
- Mild renal disease (creatinine ≤1.4 mg/dL) has minimal effect on fetal survival 1
- Moderate or severe renal insufficiency may accelerate hypertension and underlying disease, markedly reducing fetal survival 1
B. Diabetes Comorbidity
- Increases risk of preeclampsia 1
- Requires ABPM or home BP monitoring with pregnancy-validated devices 1
- Consider aspirin prophylaxis starting at 12-16 weeks 1
XIII. Postpartum Management
A. Immediate Postpartum Period
- Hypertensive disorders can worsen or initially present after delivery 7
- Account for up to 44% of pregnancy-related deaths in first 6 days postpartum 7
- Close monitoring required in early postpartum period 7
- Continue magnesium sulfate for 24 hours postpartum if used for seizure prophylaxis 1, 6
B. Medication Adjustments
- Methyldopa must be switched postnatally 2
- BP typically falls during first half of pregnancy, potentially allowing medication reduction, but close monitoring remains essential 2
XIV. Long-Term Cardiovascular Risk
A. Future Health Implications
- Hypertension during pregnancy is a recognized risk factor for future hypertension and cardiovascular disease 2, 7
- Women with chronic hypertension face significantly elevated lifetime cardiovascular risk 2
- Requires annual cardiovascular risk assessment lifelong 2
- Linked to poor long-term maternal and fetal outcomes 7
B. Long-Term Follow-Up
- Women with hypertension during pregnancy have increased cardiovascular disease risk later in life 2
- Regular cardiovascular monitoring essential for decades afterward 8
XV. Critical Pitfalls to Avoid
A. Medication Errors
- Continuing ACE inhibitors/ARBs before conception is the most critical error, as 50% of pregnancies are unplanned 2
- Using short-acting nifedipine for maintenance therapy; only extended-release formulations should be used chronically 2
- Avoiding calcium channel blockers due to outdated concerns; oral extended-release formulations are safe and effective 2
B. Management Errors
- Inadequate BP control before conception increases complications 2
- Attempting to classify preeclampsia as "mild" versus "severe" clinically 1
- Failing to recognize that gestational hypertension is not benign 1
- Delaying treatment of severe hypertension (≥160/110 mmHg) 1