What are the guidelines for managing gestational hypertension with antihypertensive medications?

Management of Gestational Hypertension with Antihypertensive Medications

For gestational hypertension, initiate antihypertensive medication at blood pressure ≥140/90 mmHg with methyldopa as the preferred first-line agent, targeting a blood pressure of 110-140/85 mmHg, and escalate to combination therapy with nifedipine or labetalol if control is inadequate. 1

Blood Pressure Thresholds for Treatment Initiation

Mild-to-Moderate Hypertension (140-169/90-109 mmHg)

• Start pharmacological treatment at BP ≥140/90 mmHg in women with gestational hypertension (with or without proteinuria), pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms at any time during pregnancy. 2

• In other circumstances without these specific features, the treatment threshold is BP ≥150/95 mmHg. 2

• Non-pharmacological management alone is insufficient at 140/90 mmHg in gestational hypertension—this threshold mandates drug therapy. 1

Severe Hypertension (≥160/110 mmHg)

• BP ≥170/110 mmHg constitutes a hypertensive emergency requiring immediate hospitalization and urgent treatment within 60 minutes. 2, 1

• Some guidelines define severe hypertension at ≥160/110 mmHg, but the ESC Task Force specifically recommends ≥170/110 mmHg as the emergency threshold. 2

First-Line Medication Selection

Preferred Agent: Methyldopa

• Methyldopa is the gold standard first-line agent for gestational hypertension due to its extensive long-term pediatric safety data and established efficacy. 1, 3

• Methyldopa has the longest safety record with documented long-term infant outcomes, making it the preferred choice endorsed by the European Society of Cardiology and multiple international obstetric societies. 1

• Important caveat: Methyldopa should be avoided postpartum due to risk of postnatal depression and must be switched to alternative agents after delivery. 2, 1

Alternative First-Line Agents

• Labetalol (oral) and long-acting nifedipine are acceptable alternatives that can be used interchangeably with methyldopa or added as second-line agents. 1, 3

• Extended-release nifedipine is preferred for maintenance therapy when used alongside methyldopa or labetalol. 1

• Labetalol serves as an excellent alternative, particularly for women without reactive airway disease. 1, 4

Target Blood Pressure Goals

• Target diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg to balance maternal protection with adequate uteroplacental perfusion. 2, 1, 5

• Reduce or cease antihypertensive drugs if diastolic BP falls below 80 mmHg to avoid compromising uteroplacental perfusion. 1, 5

Escalation Strategy for Inadequate Control

When to Add Second Agent

• If BP remains ≥140/90 mmHg despite optimal dosing of first-line medication, add a second agent (nifedipine or labetalol if not already used). 1

• Consider combination therapy earlier if BP is ≥150/100 mmHg or if there are signs of preeclampsia progression. 1

Definition of Uncontrolled Hypertension

• Uncontrollable BP is defined as inability to control maternal BP despite using ≥3 classes of antihypertensive medications in appropriate doses, which constitutes an indication for delivery regardless of gestational age. 5

Acute Management of Severe Hypertension

Medications for Hypertensive Emergency (≥170/110 mmHg)

• For acute severe hypertension requiring urgent treatment, use IV labetalol, oral methyldopa, or oral nifedipine as first-line agents. 2

• IV hydralazine is no longer the drug of choice as its use is associated with more perinatal adverse effects than other drugs. 2

• For hypertensive crises, sodium nitroprusside IV at 0.25-5.0 mg/kg/min is the drug of choice, though prolonged use risks fetal cyanide poisoning. 2

• For pre-eclampsia with pulmonary edema, nitroglycerin IV starting at 5 mg/min (gradually increased every 3-5 min to maximum 100 mg/min) is the drug of choice. 2

Critical Contraindications and Safety Warnings

Absolutely Contraindicated Medications

• ACE inhibitors, angiotensin receptor blockers (ARBs), and direct renin inhibitors are absolutely contraindicated in pregnancy due to severe fetotoxicity and renal dysgenesis. 1, 4

• Atenolol should not be used during pregnancy due to association with fetal growth retardation. 1, 4

Important Drug Interaction

• Do NOT give nifedipine (or any calcium channel blocker) concomitantly with IV magnesium sulfate due to risk of severe hypotension from potential synergism. 1, 6

• If magnesium sulfate is needed for seizure prophylaxis in preeclampsia, temporarily hold oral nifedipine or use alternative antihypertensives such as methyldopa or labetalol. 1

Monitoring and Follow-Up

• Perform serial BP measurements to confirm adequate control and monitor for progression to preeclampsia, as approximately 25% of gestational hypertension cases progress to preeclampsia. 1

• Monitor for development of proteinuria to detect progression to preeclampsia. 1

• Close supervision with limitation of activities and some bed rest in the left lateral position is recommended. 2

• A normal diet without salt restriction is advised, particularly close to delivery, as salt restriction may induce low intravascular volume. 2

Common Pitfalls to Avoid

• Failing to initiate treatment at 140/90 mmHg in gestational hypertension—this threshold fulfills guideline criteria for pharmacologic intervention and should not be delayed. 1

• Using short-acting nifedipine formulations for maintenance therapy—only extended-release formulations should be used for chronic management. 4

• Continuing methyldopa postpartum—switch to alternative agents after delivery due to depression risk. 2, 1

• Allowing diastolic BP to fall below 80 mmHg, which may compromise placental perfusion. 1, 5