Relationship between the time interval from antenatal corticosteroid administration until preterm birth and the occurrence of respiratory morbidity

The purpose of this study was to assess the relationship between neonatal respiratory morbidity and the interval between antenatal corticosteroids (ACS) administration and birth. We performed a retrospective cohort study among women who had received ACS and delivered at <34 weeks of gestation. We categorized these women in 4 groups: ACS-to-delivery interval of 0-7, 8-14, 15-21, and 22-28 days. Multivariable logistic regression analysis assessed the association between the ACS-to-delivery interval and neonatal respiratory morbidity. We included 254 neonates. Eighty-two neonates (32%) were intubated. In comparison with neonates with an ACS-to-delivery interval of 0-7 days, the risk for intubation was increased in all other groups (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.1-5.4; OR, 5.6; 95% CI, 1.8-18; and OR, 4.8; 95% CI, 0.71-32, not statistically significant, respectively). The effect of ACS decreases when the ACS-to-delivery interval exceeds 7 days. The first administration of ACS should be considered carefully