Dexamethasone dosage and course effects on respiratory outcomes in preterm twins: retrospective cohort study.

This retrospective cohort study evaluated the effects of complete, incomplete, and multiple courses of antenatal corticosteroids (ACS) on respiratory outcomes in twin preterm infants born between 28 + 0 and 36 + 6 weeks of gestation. A total of 1,115 neonates were analyzed. Primary outcomes included respiratory distress syndrome (RDS) and other adverse respiratory conditions. Infants exposed to more than one course of dexamethasone had higher requirements for CPAP support (aRR 1.400, 95% CI 1.098-1.785; P = 0.007), increased lung atelectasis (aRR 2.456, 95% CI 1.052-5.730; P = 0.038), and elevated rates of transient tachypnea of the newborn (TTNB) (aRR 1.682, 95% CI 1.194-2.368; P = 0.003). Receiving two or three doses was associated with more severe birth asphyxia (aRR 1.881, 95% CI 1.062-3.331; P = 0.030) and intraventricular hemorrhage (IVH) (aRR 2.001, 95% CI 1.150-3.481; P = 0.014). While RDS rates did not significantly differ among groups, monochorionic diamniotic (MCDA) twins who received multiple ACS courses had a higher risk of RDS (aRR 1.854, 95% CI 1.126-3.053; P = 0.015). These findings suggest that incomplete and repeated ACS courses may contribute to adverse respiratory outcomes, particularly in MCDA twins. Optimizing ACS administration is essential to improve neonatal outcomes in twin preterm pregnancies.