Antenatal Corticosteroids and Outcomes in Preterm Twins.

OBJECTIVE: To estimate whether improvement in outcomes from antenatal corticosteroid treatment in extremely and very preterm twins is similar to that observed in singletons, and to investigate whether antenatal corticosteroid treatment has different effects according to chorionicity or birth order. METHODS: This population-based study was based on an analysis of data collected by the Neonatal Research Network of Japan from 2003 to 2015 of neonates weighing 1,500 g or less at birth, from gestational ages of 24 0/7 to 31 6/7 weeks of gestation. After propensity score matching, univariate logistic and interaction analyses were performed to compare short-term (neonatal period) and medium-term (3 years of age) outcomes of the children of mothers who received antenatal corticosteroids with those of children of mothers who did not receive antenatal corticosteroids. We focused on differences between singletons and twins, between monochorionic and dichorionic twins and between the first and second twin. RESULTS: The study comprised 23,502 singletons and 6,546 twins. Antenatal corticosteroid treatment was associated with significant decreased short-term neurologic outcomes in both singletons and twins. However, antenatal corticosteroid treatment was associated with significantly decreased mortality (odds ratio [OR] 0.61; 95% CI 0.53-0.70), respiratory distress syndrome (OR 0.71, 95% CI 0.67-0.76), and cerebral palsy (OR 0.85, 95% CI 0.72-0.99) in singletons but not in twins (OR 0.89, 95% CI 0.68-1.17; OR 0.99, 95% CI 0.87-1.12; and OR 0.82, 95% CI 0.61-1.11, respectively). No association was found between chorionicity and the efficacy of antenatal corticosteroid treatment on outcomes. Further, no association was found between birth order and the efficacy of antenatal corticosteroid treatment on outcomes, except for periventricular leukomalacia and necrotizing enterocolitis (interaction: P=.02 and P=.04, respectively). CONCLUSION: Antenatal corticosteroid treatment in twins was associated with a beneficial effect on short-term neurologic outcomes only, without improvement in other short-term and medium-term outcomes. There was no difference related to chorionicity.