Population-based study on antenatal corticosteroid treatment in preterm small for gestational age and non-small for gestational age twin infants.

Objective: To assess the associations between antenatal corticosteroid use (ACU), mortality and severe morbidities in preterm, twin neonates and compare these between small for gestational age (SGA) and non-SGA twins.

Methods: Population-based study using data collected by the Israel National Very Low Birth Weight infant database from 1995 to 2012, comprising twin infants of 24-31 weeks' gestation, without major malformations. Univariate and multivariable logistic regression analyses were performed.

Results: Among the 6195 study twin infants, 784 were SGA. Among SGA neonates, ACU were associated with decreased mortality (23.9% vs. 39.2%, p < 0.0001) and composite adverse outcome including mortality or severe neonatal morbidity (43.8% vs. 56.8%, p = 0.0015), similar to the effect in non-SGA neonates (mortality 13.0% vs. 24.5%, p < 0.0001; composite outcome 34.2% vs. 44.8%, p < 0.0001). In the multivariable logistic regression analyses, ACU were associated with an almost 50% reduced mortality risk among SGA twin neonates (OR = 0.52, 95% CI 0.31-0.88) similar to the effect in non-SGA twin neonates (OR = 0.56, 95% CI 0.45-0.70), Pinteraction = 0.69. Composite adverse outcome risk was also reduced in SGA (OR = 0.78, 95% CI 0.50-1.23) and non-SGA groups (OR = 0.78, 95% CI 0.65-0.95), Pinteraction = 0.95.

Conclusions: ACU should be considered in all mothers with twin gestation, at risk for preterm delivery at 24-31 weeks, in order to improve perinatal outcome.