From the Guidelines
Labetalol and metoprolol are the safest beta blockers to use during pregnancy, with labetalol being the first choice due to its alpha and beta blocking properties and established safety profile. These medications are preferred because they have minimal risks to the developing fetus, as noted in the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy 1. The guideline states that most beta blockers, including metoprolol, bisoprolol, labetalol, pindolol, and propranolol, are generally considered safe to use during pregnancy, but atenolol has some evidence of potential fetal risk.
Key Considerations for Beta Blocker Use in Pregnancy
- Typical dosing for labetalol starts at 100 mg twice daily, which can be increased as needed up to 800 mg daily in divided doses.
- Metoprolol is an alternative option, usually started at 25-50 mg twice daily.
- Regular monitoring of maternal blood pressure, heart rate, and fetal growth is essential when using beta blockers during pregnancy.
- Beta blockers should be used at the lowest effective dose to control the condition while minimizing potential risks.
- The safety profile of these medications relates to their limited placental transfer and minimal association with fetal growth restriction compared to other antihypertensives, as supported by the 2020 AHA/ACC guideline for the diagnosis and treatment of patients with hypertrophic cardiomyopathy 1 and the 2018 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
Additional Guidance
The 2020 position paper of the ESC Council on Hypertension and the European Society of Hypertension on peripartum management of hypertension also suggests labetalol and nifedipine as first-line treatment for hypertensive emergencies during pregnancy, and notes that labetalol, nifedipine, enalapril, and metoprolol are considered safe for breastfeeding mothers 1. Overall, the choice of beta blocker during pregnancy should prioritize minimizing risks to the fetus while effectively managing the mother's condition, with labetalol and metoprolol being the preferred options due to their established safety profiles.
From the FDA Drug Label
Pregnancy:Teratogenic Effects: Pregnancy Category C: Teratogenic studies were performed with labetalol in rats and rabbits at oral doses up to approximately six and four times the maximum recommended human dose (MRHD), respectively. No reproducible evidence of fetal malformations was observed. Labetalol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus Pregnancy: Pregnancy Category C: In a series of reproductive and developmental toxicology studies, propranolol was given to rats by gavage or in the diet throughout pregnancy and lactation At doses of 150 mg/kg/day, but not at doses of 80 mg/kg/day (equivalent to the MRHD on a body surface area basis), treatment was associated with embryotoxicity (reduced litter size and increased resorption rates) as well as neonatal toxicity (deaths)
Safe beta blockers in pregnancy:
- Labetalol: may be used during pregnancy if the potential benefit justifies the potential risk to the fetus 2
- Propranolol: should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus 3 Key considerations:
- Both labetalol and propranolol are categorized as Pregnancy Category C, indicating that they should be used with caution during pregnancy.
- The decision to use these beta blockers during pregnancy should be made on a case-by-case basis, weighing the potential benefits against the potential risks to the fetus.
From the Research
Safe Beta Blockers in Pregnancy
The following beta blockers are considered safe to use during pregnancy:
- Labetalol: This alpha-beta blocker has been shown to be effective in controlling hypertension in pregnant women, with a lower risk of fetal growth restriction compared to atenolol 4, 5.
- Atenolol: Although it has been associated with a higher risk of fetal growth restriction, atenolol is still considered safe to use in pregnancy, especially when the benefits outweigh the risks 4, 6.
- Methyldopa: This beta blocker is often used as a first-line treatment for hypertension in pregnancy, and is considered safe for both the mother and the fetus 7, 6.
Key Considerations
When using beta blockers in pregnancy, it is essential to:
- Monitor fetal growth and development closely, as some beta blockers may increase the risk of growth restriction 4, 6.
- Choose the beta blocker that is most suitable for the individual patient, taking into account the severity of hypertension and any underlying medical conditions 8, 7.
- Be aware of the potential risks and benefits of beta blocker use in pregnancy, and discuss these with the patient to ensure informed decision-making 8, 6.
Beta Blocker Comparison
Studies have compared the safety and efficacy of different beta blockers in pregnancy, including:
- Labetalol vs. atenolol: Labetalol has been shown to have a more favorable effect on fetal growth and development compared to atenolol 4.
- Beta blockers vs. other antihypertensive agents: Beta blockers have been compared to other antihypertensive agents, such as methyldopa and hydralazine, with varying results 6.
- Beta blockers vs. placebo: Beta blockers have been shown to be effective in reducing the risk of severe hypertension and the need for additional antihypertensive drugs in pregnancy 6.