Maternofetal pharmacokinetics and fetal lung responses in chronically catheterized sheep receiving constant, low-dose infusions of betamethasone phosphate

Constant maternal betamethasone infusions delivering substantially lower fetal and maternal betamethasone maximal concentrations than those achieved with current clinical treatment protocols were associated with dose-dependent changes in glucocorticoid-response markers in the fetal lung. Further studies to determine the minimally efficacious dose of steroids for improving outcomes in preterm infants should be viewed as a priority.