What is the preferred pressor in pregnancy?

Preferred Pressors in Pregnancy

For hypertensive emergencies in pregnancy, intravenous labetalol is the first-line vasopressor of choice, with oral methyldopa and nifedipine as effective alternatives. 1

Vasopressors for Hypertensive Disorders in Pregnancy

First-Line Agents

• Intravenous labetalol is recommended as the first-line agent for severe hypertension in pregnancy requiring immediate treatment 1, 2
• Oral methyldopa is considered the first-line agent for non-severe hypertension management during pregnancy 2
• Oral nifedipine (long-acting) is an effective alternative for non-severe hypertension management 1, 2

Second-Line Agents

• Hydralazine may be considered in the acute management of severe hypertension or preeclampsia, though it is no longer the drug of first choice due to more perinatal adverse effects compared to other medications 1
• For hypertensive crisis, sodium nitroprusside can be used as an IV infusion at 0.25-5.0 mg/kg/min, but prolonged treatment should be avoided due to risk of fetal cyanide poisoning 1
• Nitroglycerin (glyceryl trinitrate) is the drug of choice specifically for preeclampsia associated with pulmonary edema 1

Blood Pressure Targets in Pregnancy

• Current evidence supports maintaining blood pressure between 110-135/85 mmHg to reduce the risk of accelerated maternal hypertension while minimizing impairment of fetal growth 1
• A systolic blood pressure ≥170 mmHg or diastolic blood pressure ≥110 mmHg should be considered an emergency requiring immediate hospitalization 1
• Treatment should be deintensified if blood pressure falls below 90/60 mmHg to prevent compromised uteroplacental perfusion 1

Contraindicated Medications in Pregnancy

• ACE inhibitors, angiotensin receptor blockers (ARBs), direct renin inhibitors, and mineralocorticoid receptor antagonists are contraindicated during pregnancy 1, 2
• These medications can cause fetal renal dysplasia, oligohydramnios, pulmonary hypoplasia, and intrauterine growth restriction 1
• Women planning pregnancy or who become pregnant while on these medications should be switched to pregnancy-safe alternatives immediately 1

Vasopressors for Hypotension During Cesarean Section

• Phenylephrine is currently preferred over ephedrine for managing spinal anesthesia-induced hypotension during cesarean delivery 3, 4
• Phenylephrine is associated with better fetal acid-base status compared to ephedrine, which crosses the placenta more readily and can cause fetal metabolic acidosis 4, 5
• Norepinephrine appears to have similar effects on fetal cerebral perfusion as phenylephrine when used at comparable doses 6

Management Algorithm for Hypertension in Pregnancy

1. For non-severe hypertension (BP 140-159/90-109 mmHg):

   • First-line: Oral methyldopa 1, 2
   • Alternatives: Oral labetalol or long-acting nifedipine 1
   • Target BP: 110-135/85 mmHg 1

2. For severe hypertension (BP ≥160/110 mmHg):

   • First-line: IV labetalol 1, 2
   • Alternatives: Oral methyldopa, oral nifedipine, or IV hydralazine 1
   • For hypertensive crisis: IV sodium nitroprusside (short-term use only) 1
   • For preeclampsia with pulmonary edema: IV nitroglycerin 1

3. For hypotension during cesarean section:

   • First-line: Phenylephrine infusion 3, 4
   • Alternative: Norepinephrine 6
   • Avoid: Prolonged use of ephedrine due to risk of fetal acidosis 4

Special Considerations

• Diuretics are generally not recommended for blood pressure management in pregnancy but may be used in late-stage pregnancy if needed for volume management 1
• Beta-blockers other than atenolol may be used if necessary; atenolol specifically is not recommended 1
• Low-dose aspirin (100-150 mg/day) starting at 12-16 weeks of gestation is recommended for pregnant individuals with diabetes to reduce preeclampsia risk 1
• Regular monitoring of maternal blood pressure and fetal growth is essential throughout pregnancy 2