Timing of antenatal corticosteroids and neonatal pulmonary mechanics

Abstract

Objective: We sought to compare lung mechanics in infants treated with multiple courses of antenatal corticosteroids with those in matched control infants delivered >7 days from dosing and those of matched untreated infants. Study Design: Eighteen infants who received multiple courses of corticosteroids and were delivered within 7 days of dosing were matched with 18 infants who received 1 course of corticosteroids >7 days before delivery (remote) and 18 untreated infants. Respiratory compliance and functional residual capacity were measured within 36 hours. Differences were compared by analysis of variance. Results: Infant demographics were similar. Respiratory compliance was higher in the multiple-course group than in the remote or untreated group ( P < .02). Functional residual capacity was higher in the multiple-course group than in the untreated group ( P < .05) but similar to that found in the remote group. Conclusion: Babies delivered after multiple courses of corticosteroids and within 7 days of dosing demonstrated improved respiratory compliance compared with untreated and remotely treated infants. This suggests that the enzyme system responsible for surfactant production can be repetitively induced despite prior treatment with corticosteroids. The increased functional residual capacity in remotely treated infants may reflect a maturation of lung architecture independent of surfactant production. (Am J Obstet Gynecol 2000;183:895-9.)