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

OBJECTIVE: The purpose of this study was to assess the relationship between neonatal respiratory morbidity and the interval between antenatal corticosteroids (ACS) administration and birth. STUDY DESIGN: 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. RESULTS: 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). CONCLUSION: The effect of ACS decreases when the ACS-to-delivery interval exceeds 7 days. The first administration of ACS should be considered carefully.