Antenatal Betamethasone: Formulation, Dosing, and Clinical Indications

Formulation & Dosing Recommendations

• The Society for Maternal‑Fetal Medicine (SMFM) recommends the dual‑salt formulation (betamethasone sodium phosphate + betamethasone acetate) for antenatal surfactant stimulation, supported by Grade 1A evidence. [1][3]
• The recommended dose is 12 mg administered intramuscularly per injection, with two injections given 24 hours apart. [1][5]
• The regimen should be delivered exclusively by intramuscular injection; other routes are not advised. 1

Indications by Gestational Age

• Late‑preterm (34 0/7 – 36 6/7 weeks): Offer the standard 2‑dose 12 mg dual‑salt regimen to singleton pregnancies at high risk of delivery within 7 days and before 37 weeks. [1][3]
• Earlier preterm (<34 weeks): Apply the same dual‑salt formulation and dosing schedule as for late‑preterm pregnancies. [1][8]

Contraindications & Clinical Caveats

• Contraindicated in women with pregestational diabetes mellitus because of an increased risk of severe neonatal hypoglycemia. [3][7]
• Avoid in low‑risk patients who have a low likelihood of delivering before 37 weeks, as the potential harms may outweigh benefits. [3][9]