The effect of single or multiple courses of antenatal corticosteroid therapy on neonatal respiratory distress syndrome in singleton versus twin pregnancies

Background: Antenatal corticosteroid (ACS) treatment is widely used for the prevention of respiratory distress syndrome (RDS) in preterm infants. However, the efficacy and safety of ACS treatment remains controversial in twin pregnancies.
Aims: To investigate the effect of ACS therapy, single or multiple courses, on the incidence of neonatal RDS in singleton and twin pregnancies.
Methods: We retrospectively evaluated the pregnancy and neonatal outcomes of 450 singleton and 117 twin pregnancies delivered at 24–34 weeks of gestation due to preterm labour or preterm premature rupture of membranes. The subjects were categorised into four groups according to ACS exposure: 0, 1, 2 and ≥ 3 courses.
Results: Overall, RDS occurred more frequently in twins compared to singletons (41.0% vs 25.3%, P  < 0.001). In singleton pregnancy, the incidence of RDS was significantly lower in the ACS user groups than in the non-user group, with the lowest incidence in the multiple course groups. An increase in the number of courses of ACS was associated with a reduction in the incidence of RDS (odds ratio 0.349, 95% confidence interval 0.226, 0.537, P  < 0.001) independent of confounding variables. In twin pregnancies, however, the incidence of RDS was not significantly different in comparisons among the four groups.
Conclusion: Multiple courses of ACS were associated with a significantly decreased risk of RDS in singleton pregnancies. However, the current standard dose or interval for ACS administration in singleton pregnancy, as either a single or multiple courses, did not reduce RDS in twins.