Prenatal administration of betamethasone for prevention of respiratory distress syndrome.

The outcome of 114 infants of birth weight 750 to 1,750 gm who received prenatal betamethasone therapy was compared retrospectively to that of 138 infants delivered to untreated women. The incidence of respiratory distress syndrome in all treated infants was 37.7% compared with 50.7% (P = 0.05) in untreated infants. There was no apparent benefit of therapy among infants delivering less than 48 hours after the first dose and among infants less than 750 gm birth weight. Among infants delivering two to ten days after therapy, RDS 25.0 vs 50.7%) and mortality (8.9 vs 22.5%) were significantly reduced. Among surviving infants with RDS, fewer infants in the two to ten-day treated group required oxygen at FIO2 greater than 0.5 for more than 24 hours. Our findings confirm previous reports that prenatal glucocorticoid treatment reduces the incidence of RDS and mortality in premature infants. In addition, they indicate that therapy is more effective when delivery is delayed at least two days, that very small premature infants do not benefit from treatment, and that RDS may be less severe after prenatal exposure to betamethasone.