MATERNAL CORTICOSTEROID AND TOCOLYTIC TREATMENT AND MORBIDITY AND MORTALITY IN VERY-LOW-BIRTH-WEIGHT INFANTS

In 1972 Liggins and Howie(1) demonstrated that maternal administration of corticosteroids before preterm delivery resulted in a 65% decrease in the rate of respiratory distress syndrome (RDS) and an 80% decrease in neonatal mortality in infants of treated mothers compared with controls. These findings have since been confirmed, both in single and multicenter randomized trials and with the use of meta-analytic techniques.(2-6) However, the gestational age range at which these benefits occur is less certain. Although the evidence is very strong that maternal corticosteroid therapy is beneficial to infants delivered between 29 and 34 weeks' gestation, it is not clear whether infants delivered at 24 to 28 weeks also achieve significant benefit from maternal corticosteroid therapy.(4) Although beta-sympathomimetic use is almost certainly associated with a delay in delivery for 24 to 48 hours,(7) evidence for the effectiveness of tocolytic therapy to achieve significant improvement in any neonatal outcome such as mortality, RDS, or other neonatal morbidity is less convincing,(8) although the use of these agents is common. Of concern is recent evidence that in very-low-birth-weight infants maternal tocolytic use may be associated with a significantly increased risk of intraventricular hemorrhage.(9-11) Given the lack of evidence for effectiveness of tocolytics used independently, their use is often justified as a delaying tactic so that corticosteroids will have time to be administered and have a significant effect. The Canadian Preterm Labor Study(12) suggested that because of a favorable trend in mortality rates at 24 to 27 weeks' gestation associated with ritodrine therapy, perhaps ritodrine should be used in that gestational age range to facilitate the use of corticosteroids, a well-tested and beneficial therapy. Therefore the objective of this study was to examine the relationship between maternal corticosteroid and tocolytic use, separately and in combination, and neonatal morbidity and mortality in a large group of infants delivered at 24 to 28 weeks.