Safe Muscle Relaxants During Pregnancy
Non-pharmacological approaches should be prioritized as first-line treatment for muscle cramps during pregnancy, as most muscle relaxants have limited safety data or are contraindicated during pregnancy. 1
Non-Pharmacological Management (First-Line)
The safest approach to managing muscle cramps during pregnancy involves:
- Regular stretching of calf muscles, especially before bedtime
- Maintaining adequate hydration
- Engaging in moderate-intensity physical activity (150 minutes weekly)
- Oral magnesium supplementation (300 mg daily) 1
These non-pharmacological approaches are recommended by both the European Society of Cardiology and the American College of Obstetricians and Gynecologists as the preferred initial management strategy.
Pharmacological Options
When non-pharmacological approaches fail, medication options are limited:
Potentially Safer Options:
- Metoprolol - If absolutely necessary after the first trimester, this beta-1 selective blocker may be used with caution due to its lower incidence of fetal growth retardation 1
Contraindicated Muscle Relaxants:
- Cyclobenzaprine - Associated with increased risk of multiple birth defects including cleft palate (OR = 4.79), anorectal atresia/stenosis (OR = 6.91), and cardiac defects 2
- Metaxalone - FDA label states it "should not be used in women who are or may become pregnant and particularly during early pregnancy unless, in the judgment of the physician, the potential benefits outweigh the possible hazards" 3
- Atracurium and Mivacurium - Contraindicated during pregnancy according to the National Comprehensive Cancer Network 1
- Propranolol, Procainamide, Quinidine, and Sotalol - Should be avoided during pregnancy 1
Special Considerations for Surgical Settings
If muscle relaxation is required for surgical procedures during pregnancy:
- Rocuronium and Vecuronium are considered safer alternatives for surgical procedures 1
- Multidisciplinary management involving surgical, anesthesia, and perioperative medical teams is recommended
Monitoring and Safety Precautions
When muscle relaxants must be used during pregnancy:
- Monitor for fetal bradycardia
- Watch for potential effects on fetal growth
- Be alert for hypoglycemia in the neonate 1
Warning Signs
Pregnant women should stop physical activity and consult healthcare providers if experiencing:
- Persistent or severe muscle cramps
- Excessive shortness of breath
- Severe chest pain
- Regular and painful uterine contractions
- Vaginal bleeding 1
The evidence supporting the use of muscle relaxants during pregnancy is limited, and the potential risks to the developing fetus generally outweigh the benefits for most muscle relaxants. When medication is absolutely necessary, metoprolol may be considered with caution after the first trimester, but only after non-pharmacological approaches have failed.