What is the management plan for pregnancy-induced hypertension?

Management of Pregnancy-Induced Hypertension

The management of pregnancy-induced hypertension requires prompt treatment of blood pressure ≥140/90 mmHg in women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage, using first-line agents such as methyldopa, labetalol, or nifedipine, while hospitalization is mandatory for severe hypertension (≥170/110 mmHg). 1, 2

Classification and Diagnosis

• Hypertension in early pregnancy (before 20 weeks) is classified as pre-existing hypertension, which complicates 1-5% of pregnancies 2
• Gestational hypertension is defined as hypertension that develops after 20 weeks of gestation without proteinuria 1, 2
• Pre-eclampsia is gestational hypertension with clinically significant proteinuria (≥0.3 g/day in a 24h urine collection or ≥30 mg/mmol urinary creatinine) 1, 2
• Pre-existing hypertension plus superimposed gestational hypertension with proteinuria occurs when pre-existing hypertension worsens with protein excretion ≥3 g/day after 20 weeks gestation 1, 2

Treatment Thresholds and Targets

• For women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage, initiate treatment at BP ≥140/90 mmHg 1, 2
• For all other pregnant women with hypertension, initiate treatment at BP ≥150/95 mmHg 1, 2
• Target diastolic BP should be 85 mmHg and systolic BP between 110-140 mmHg to ensure adequate uteroplacental perfusion 1
• Reduce or cease antihypertensive drugs if diastolic BP falls <80 mmHg 1
• Severe hypertension (SBP ≥170 mmHg or DBP ≥110 mmHg) is considered an emergency requiring immediate hospitalization 1, 3

Non-Pharmacological Management

• Implement non-pharmacological management for pregnant women with SBP of 140-150 mmHg or DBP of 90-99 mmHg 1, 2
• Recommend a normal diet without salt restriction, particularly close to delivery, as salt restriction may induce low intravascular volume 1, 2
• Advise limitation of activities and some bed rest in the left lateral position 1, 2
• Consider low-dose acetylsalicylic acid (75-100 mg/day) prophylactically in women with a history of early-onset (<28 weeks) pre-eclampsia, administered at bedtime starting before 16 weeks gestation 1, 2

Pharmacological Management

First-Line Medications

• Oral methyldopa is a first-line agent with the longest safety record (7.5 years of infant follow-up) 1, 4
• Labetalol (oral or IV) is equally effective as methyldopa and suitable for urgent BP control 1, 5
• Nifedipine (preferably extended-release) is an effective first-line calcium channel blocker 1, 6
• Oxprenolol can be used as an alternative beta-blocker 1

Second/Third-Line Medications

• Hydralazine and prazosin can be used as second or third-line agents 1
• For hypertensive crises, sodium nitroprusside can be given as an IV infusion (0.25-5.0 mg/kg/min), but prolonged treatment should be avoided due to risk of fetal cyanide poisoning 1
• For pre-eclampsia with pulmonary edema, nitroglycerin is the drug of choice (IV infusion starting at 5 mg/min, gradually increased to maximum 100 mg/min) 1

Contraindicated Medications

• ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated throughout pregnancy due to severe fetotoxicity 1, 2
• Avoid methyldopa post-partum due to risk of post-natal depression 1

Management of Severe Hypertension

• BP ≥170/110 mmHg requires urgent treatment in a monitored setting 1, 3
• First-line agents for severe hypertension include:
  • Oral nifedipine 1
  • IV labetalol 1, 5
  • IV hydralazine 1
• For pre-eclampsia with severe hypertension or neurological signs/symptoms, administer magnesium sulfate for convulsion prophylaxis 1

Monitoring Requirements

Maternal Monitoring

• Regular BP monitoring throughout pregnancy 2
• In pre-eclampsia, perform clinical assessment including testing for clonus 1
• Monitor for proteinuria if not already present 1
• Perform blood tests at least twice weekly for hemoglobin, platelet count, liver enzymes, creatinine, and uric acid in pre-eclampsia 1
• Watch for warning signs of worsening condition (headache, visual disturbances, epigastric pain) 2, 3

Fetal Monitoring

• Initial assessment to confirm fetal well-being 1
• In fetal growth restriction, perform serial ultrasound surveillance 1
• Monitor amniotic fluid and umbilical artery Doppler more frequently if fetal growth restriction is present 1

Delivery Considerations

• Induce delivery in gestational hypertension with proteinuria if adverse conditions are present (visual disturbances, coagulation abnormalities, fetal distress) 1
• Deliver women with pre-eclampsia at 37 weeks (and zero days) gestation 1
• Consider earlier delivery if any of the following develop:
  • Repeated episodes of severe hypertension despite treatment with 3 classes of antihypertensives
  • Progressive thrombocytopenia
  • Progressively abnormal renal or liver enzyme tests
  • Pulmonary edema
  • Abnormal neurological features
  • Non-reassuring fetal status 1

Post-Partum Management

• Monitor BP closely as it typically rises after delivery over the first 5 days 1
• Continue antihypertensive medications with gradual tapering rather than abrupt cessation 2
• Avoid methyldopa post-partum due to risk of post-natal depression 1
• Women with pre-existing hypertension should continue their current medication except ACE inhibitors, ARBs, and direct renin inhibitors 1

Long-Term Considerations

• Women who develop gestational hypertension or pre-eclampsia have increased risk of hypertension and stroke in later life 1
• The relative risk of developing ischemic heart disease after pre-eclampsia is more than twice as high compared to women with normal pregnancies 1
• Risk of developing hypertension is almost four-fold higher after pre-eclampsia 1
• Women with early-onset pre-eclampsia (delivery before 32 weeks), stillbirth, or fetal growth restriction are at highest risk 1
• Recommend lifestyle modifications, regular BP monitoring, and control of metabolic factors after delivery 1, 2
• Annual medical review is recommended lifelong for women who had hypertensive disorders of pregnancy 2

Common Pitfalls and Caveats

• Do not use ACE inhibitors, ARBs, or direct renin inhibitors at any point during pregnancy 1, 2
• Avoid methyldopa post-partum due to risk of post-natal depression 1
• Do not restrict salt intake, especially close to delivery 1, 2
• Do not allow diastolic BP to fall below 80 mmHg to maintain adequate uteroplacental perfusion 1
• Never delay treatment of severe hypertension (≥170/110 mmHg) as it is a medical emergency 1, 3
• Do not attempt to distinguish between mild and severe pre-eclampsia clinically, as all cases may rapidly deteriorate 1