What are the guidelines for using propranolol (beta-blocker) during pregnancy?

Propranolol Use During Pregnancy

Direct Recommendation

Propranolol can be used during pregnancy when clinically indicated for arrhythmias or other cardiovascular conditions, but should be avoided during the first trimester if possible, used at the lowest effective dose, and requires enhanced fetal monitoring for growth retardation. 1, 2

Clinical Indications and Classification

When Propranolol Is Appropriate

• For acute conversion of paroxysmal supraventricular tachycardia (PSVT): Propranolol receives a Class IIa recommendation (reasonable to use) 1
• For prophylactic therapy of SVT: Propranolol receives a Class IIa recommendation with Level B evidence 1
• For long-term management of idiopathic sustained ventricular tachycardia: Propranolol receives a Class I recommendation (should be used) 1
• Propranolol is considered a relatively safe first-line agent for chronic prophylaxis during pregnancy due to its longer safety record compared to other antiarrhythmic medications 2, 3

FDA Classification

• Propranolol is FDA Pregnancy Category C, meaning risk cannot be ruled out but potential benefits may warrant use 1, 4

Critical Timing Considerations

First Trimester Avoidance

• Beta-blockers including propranolol should be avoided during the first trimester if possible, when the risk of congenital malformations and growth retardation is greatest 1, 2
• If treatment cannot be delayed, the decision must weigh maternal hemodynamic compromise against fetal risk 1

Second and Third Trimester Use

• Propranolol can be used more safely after the first trimester for ongoing management 1, 2
• Hemodynamic load is highest during the second and third trimesters, requiring closer monitoring 2, 3

Fetal Risks and Adverse Effects

Growth Retardation (Primary Concern)

• Intrauterine growth retardation is the most significant and consistent adverse effect associated with propranolol, particularly with first-trimester exposure 1, 2, 3, 5
• This risk appears statistically significant across multiple studies 5

Other Potential Neonatal Effects

• Fetal bradycardia may occur and requires surveillance 2, 3
• Neonatal hypoglycemia has been reported but is not invariable and cannot be statistically correlated with chronic propranolol therapy 5
• Neonatal hyperbilirubinemia, polycythemia, and apnea have been reported but are not consistently linked to propranolol use 5
• Respiratory depression at birth may occur 4

Required Monitoring Protocol

Maternal Monitoring

• Start with the lowest effective dose and titrate according to clinical response 2, 3
• More careful monitoring and dose adjustments are necessary because pregnancy affects drug absorption, bioavailability, and elimination 1

Fetal Monitoring

• Serial ultrasound examinations for fetal growth monitoring are essential 2, 3
• Serial echocardiography may be warranted, particularly during the second or third trimester when hemodynamic load is highest 2, 3
• Surveillance for fetal bradycardia should be maintained throughout pregnancy 2, 3

Neonatal Monitoring at Birth

• Adequate facilities for monitoring infants at birth should be available for bradycardia, hypoglycemia, and respiratory depression 4
• Monitor for rare adverse effects including metabolic abnormalities in the newborn 3
• In severely affected infants, short-term pharmacological management may be required 3

Comparison with Other Beta-Blockers

Preferred Alternatives

• Metoprolol is also considered safe during pregnancy and receives a Class I recommendation for prophylactic SVT therapy 1, 2
• Metoprolol may be preferred by some clinicians and should be considered if growth concerns arise with propranolol 2, 3
• Sotalol is a Class B agent (safer category) but has more limited experience 1

Beta-Blockers to Avoid

• Atenolol should NOT be used for any arrhythmia during pregnancy (Class III recommendation - should not be used) 1, 2
• Atenolol is associated with more pronounced intrauterine growth retardation, especially with early pregnancy exposure and longer duration of use 1, 2, 3
• Atenolol is FDA Category D (positive evidence of fetal risk) 1

Clinical Decision Algorithm

Step 1: Assess Clinical Necessity

• Use propranolol only if symptoms are intolerable or if tachycardia causes hemodynamic compromise 1
• In patients with mild symptoms and structurally normal hearts, provide reassurance without drug therapy 1

Step 2: Timing Evaluation

• If first trimester: Delay treatment if possible; if not possible, use lowest effective dose with informed consent about growth retardation risk 1, 2
• If second or third trimester: Propranolol can be initiated with appropriate monitoring 2

Step 3: Dosing Strategy

• Start with the lowest effective dose 2, 3
• Titrate according to clinical response 2, 3

Step 4: Monitoring Implementation

• Establish baseline fetal growth parameters 2
• Schedule serial ultrasounds for growth monitoring 2, 3
• Consider serial echocardiography in second and third trimesters 2, 3
• Monitor for fetal bradycardia throughout pregnancy 2, 3

Step 5: Alternative Consideration

• If growth retardation develops, consider switching to metoprolol 2, 3
• Never switch to atenolol 1, 2

Step 6: Delivery Planning

• Ensure adequate neonatal monitoring facilities are available at delivery 4
• Arrange early follow-up after hospital discharge 3

Common Pitfalls to Avoid

• Do not use atenolol as an alternative - it has worse fetal outcomes than propranolol 2, 3
• Do not skip fetal growth monitoring - growth retardation is the most consistent adverse effect 2, 5
• Do not use higher doses than necessary - dose-dependent effects may worsen outcomes 2, 3
• Do not assume all reported neonatal complications are drug-related - many may be secondary to maternal disease or fetal distress in high-risk pregnancies 1, 5

Special Considerations

Lactation

• Propranolol is excreted in human milk; caution should be exercised when administering to nursing women 4

Drug Interactions During Pregnancy

• NSAIDs may blunt the antihypertensive effect of propranolol 4
• Warfarin concentrations increase when co-administered with propranolol; monitor prothrombin time 4