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% decreas e in neonatal mortality in infants of treated mothers compared with co ntrols. These findings have since been confirmed, both in single and m ulticenter randomized trials and with the use of meta-analytic techniq ues.(2-6) However, the gestational age range at which these benefits o ccur is less certain. Although the evidence is very strong that matern al corticosteroid therapy is beneficial to infants delivered between 2 9 and 34 weeks' gestation, it is not clear whether infants delivered a t 24 to 28 weeks also achieve significant benefit from maternal cortic osteroid therapy.(4) Although beta-sympathomimetic use is almost certa inly associated with a delay in delivery for 24 to 48 hours,(7) eviden ce for the effectiveness of tocolytic therapy to achieve significant i mprovement in any neonatal outcome such as mortality, RDS, or other ne onatal morbidity is less convincing,(8) although the use of these agen ts is common. Of concern is recent evidence that in very-low-birth-wei ght infants maternal tocolytic use may be associated with a significan tly increased risk of intraventricular hemorrhage.(9-11) Given the lac k of evidence for effectiveness of tocolytics used independently, thei r use is often justified as a delaying tactic so that corticosteroids will have time to be administered and have a significant effect. The C anadian 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 gestationa l age range to facilitate the use of corticosteroids, a well-tested an d beneficial therapy. Therefore the objective of this study was to exa mine the relationship between maternal corticosteroid and tocolytic us e, separately and in combination, and neonatal morbidity and mortality in a large group of infants delivered at 24 to 28 weeks.