What are the management guidelines for hypertension in a pregnant woman?

Management Guidelines for Hypertension in Pregnant Women

In pregnant women with hypertension, pharmacological treatment should be initiated at a blood pressure (BP) ≥140/90 mmHg for women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms. 1

Classification of Hypertension in Pregnancy

• Hypertension in early pregnancy (before 20 weeks) is typically 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
• Pre-eclampsia is gestational hypertension with clinically significant proteinuria (≥0.3 g/day in a 24h urine collection or ≥30 mg/mmol urinary creatinine in a spot random urine sample) 1
• 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

Treatment Thresholds and Targets

• For women with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage, treatment should be initiated at BP ≥140/90 mmHg 1
• In all other pregnant women with hypertension, treatment should be initiated at BP ≥150/95 mmHg 1
• Target BP should be below 140/90 mmHg but not below 80 mmHg for diastolic BP to ensure adequate uteroplacental perfusion 1
• Severe hypertension (SBP ≥170 mmHg or DBP ≥110 mmHg) in a pregnant woman is considered an emergency requiring hospitalization 1

Non-Pharmacological Management

• Non-pharmacological management is recommended for pregnant women with SBP of 140-150 mmHg or DBP of 90-99 mmHg 1
• A normal diet without salt restriction is advised, particularly close to delivery, as salt restriction may induce low intravascular volume 1
• Limitation of activities and some bed rest in the left lateral position may be beneficial 1, 2
• Low-dose acetylsalicylic acid (75-100 mg/day) is recommended prophylactically in women with a history of early-onset (<28 weeks) pre-eclampsia, administered at bedtime starting before 16 weeks gestation 1, 2
• Weight reduction during pregnancy is not recommended for obese women 1

Pharmacological Management

First-line Medications

• Dihydropyridine calcium channel blockers (preferably extended-release nifedipine), labetalol, and methyldopa are recommended as first-line BP-lowering medications for treating hypertension in pregnancy 1, 2
• Methyldopa has the longest safety record with adequate infant follow-up (7.5 years) 1
• Labetalol has efficacy comparable to methyldopa and can be given intravenously in cases of severe hypertension 1, 2

Severe Hypertension Management

• For severe hypertension (SBP ≥170 mmHg or DBP ≥110 mmHg), immediate pharmacological treatment with IV labetalol, oral methyldopa, or nifedipine should be initiated 1
• The drug of choice in hypertensive crises is sodium nitroprusside (IV infusion at 0.25-5.0 mg/kg/min), but prolonged treatment is associated with risk of fetal cyanide poisoning 1
• For pre-eclampsia with pulmonary edema, nitroglycerine (glyceryl trinitrate) is the drug of choice 1

Contraindicated Medications

• ACE inhibitors, ARBs, and direct renin inhibitors are strictly contraindicated throughout pregnancy due to severe fetotoxicity 1, 2
• IV hydralazine is no longer the drug of choice as its use is associated with more perinatal adverse effects than other drugs 1

Monitoring and Follow-up

• Regular BP monitoring is essential throughout pregnancy 2
• Monitor for signs of worsening hypertension or development of pre-eclampsia (headache, visual disturbances, epigastric pain) 2
• Evaluate for proteinuria to detect pre-eclampsia 2
• Induction of delivery is indicated in gestational hypertension with proteinuria with adverse conditions such as visual disturbances, coagulation abnormalities, or fetal distress 1

Postpartum Management

• Continue antihypertensive medications postpartum with gradual tapering rather than abrupt cessation 3
• Safe antihypertensive medications for breastfeeding mothers include labetalol, nifedipine, methyldopa, enalapril, and beta-blockers 3
• Diuretics may reduce milk production and are generally not preferred in breastfeeding women 3
• All women should be reviewed at 3 months postpartum to ensure BP, urinalysis, and laboratory abnormalities have normalized 3

Long-term Considerations

• Women with hypertensive disorders of pregnancy have significant long-term cardiovascular risks and require ongoing monitoring 3, 4
• Annual medical review is advised lifelong for women who had hypertensive disorders of pregnancy 3
• Aim to achieve pre-pregnancy weight by 12 months and adopt a healthy lifestyle that includes regular exercise, healthy diet, and maintaining ideal body weight 3

Common Pitfalls and Caveats

• Avoid excessive BP reduction as this may impair uteroplacental perfusion and jeopardize fetal development 1, 2
• Be vigilant for signs of worsening hypertension or development of pre-eclampsia as pregnancy progresses 2
• NSAIDs for postpartum analgesia should be avoided in women with pre-eclampsia unless other analgesics are not effective 3
• Women with persisting hypertension under age 40 should be assessed for secondary causes of hypertension 3, 5