Betamethasone for lung maturation: testing dose and formulation in fetal sheep

Am J Obstet Gynecol. 2007 Nov;197(5):523.e1-6. doi: 10.1016/j.ajog.2007.04.004.


Objective: We evaluated lung maturation responses to the mixture of betamethasone phosphate (Beta-PO4) + betamethasone acetate (Beta-Ac) in comparison to Beta-PO4 or Beta-Ac in fetal sheep.

Study design: Ewes carrying singleton pregnancies at 122 days of gestation were randomized to single doses of 0.5 mg/kg Beta-PO4 + Beta-Ac, 0.25 mg/kg Beta-PO4, 0.5 mg/kg Beta-PO4, or 0.25 mg/kg Beta-Ac given 48 hours before delivery. These treatments were compared with saline placebo and 2 doses of 0.5 mg/kg Beta-PO4 + Beta-Ac that were given 48 and 24 hours before delivery. Fetal lung maturation was evaluated.

Results: The 2 doses of the Beta-PO4 + Beta-Ac mixture gave the best lung maturation. Single doses of the Beta-PO4 + Beta-Ac mixture and Beta-Ac alone also induced lung maturation. There were no consistent responses to either dose of Beta-PO4.

Conclusion: Beta-PO4 alone is ineffective with the dosing schedule used; Beta-Ac can induce lung maturation. However, the best responses result from the mixture of Beta-PO4 + Beta-Ac.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Betamethasone / administration & dosage
  • Betamethasone / analogs & derivatives*
  • Female
  • Fetal Organ Maturity / drug effects*
  • Glucocorticoids / administration & dosage*
  • Lung / embryology*
  • Male
  • Pregnancy
  • Pulmonary Surfactant-Associated Proteins / analysis
  • Pulmonary Surfactants / analysis
  • Random Allocation
  • Respiration, Artificial
  • Sheep


  • Glucocorticoids
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants
  • betamethasone sodium phosphate
  • Betamethasone