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Editor—Randomised, placebo controlled trials of antenatal corticosteroid administration have not shown a significant reduction in the incidence of respiratory distress syndrome (RDS) in premature twins.1 Subsequent retrospective studies examining the effect of steroids on twin pregnancies have shown conflicting results.2 3
Further to our recent article,4 we have investigated the relation between respiratory distress and antenatal corticosteroid treatment in premature twins from the same historical cohort selected from the Australia and New Zealand Neonatal Network (ANZNN) 1995 database. To reflect best possible clinical practice, the analysis was restricted to the effects of an optimal steroid course (two doses of corticosteroids given, the first dose of which was received more than 24 hours and less than eight days before the infant's birth) compared with no steroid treatment.
As shown in table 1, treatment with antenatal steroids resulted in a significantly lower incidence of RDS and surfactant use. The reduction from 18% to 11% in the risk of mortality was not significant (p = 0.08). Recent advances in obstetrics and neonatology could explain the absence of an antenatal steroid associated reduction in mortality.5 There was no statistically significant association between optimal steroid use and the outcome measures of days of intermittent positive pressure ventilation, days of oxygen, oxygen at 36 weeks corrected gestational age, severe intraventricular haemorrhage, or the number of proven infection episodes. Gestation, sex, race, and birth order did not modify the association between antenatal steroid treatment and RDS incidence.
The sample examined in this study is over twice the size of the most recent retrospective analysis, which reported no antenatal steroid associated reduction of RDS in twins.3 However, the reduction in RDS incidence observed in our study is less than that seen in singleton infants (odds ratio 0.35, 95% confidence interval 0.26 to 0.46).5 Optimal steroid treatment may be less effective in multiple gestation pregnancies because the increased volume of distribution in these mothers may reduce the plasma level of steroids to which the fetuses are exposed.1
Data used for this study came from the Australia and New Zealand Neonatal Network.