Effects of antenatal corticosteroids on respiratory distress syndrome in preterm infants across gestational age strata

Abstract Background Antenatal corticosteroids (ACS) are widely used to promote fetal lung maturation and reduce the incidence of neonatal respiratory distress syndrome (RDS). However, the efficacy of ACS varies across gestational ages (GA) and clinical contexts. This study aimed to evaluate the association between ACS exposure and RDS in preterm infants and to identify factors that modify this association. Methods This single-center retrospective cohort study, conducted at the First People's Hospital of Yinchuan, included 504 preterm neonates (GA < 37 weeks) born between 2020 and 2024. ACS exposure, demographic characteristics, and clinical outcomes were extracted from medical records. Multivariable logistic regression was used to assess the independent association between ACS and RDS, with subgroup analyses stratified by GA and delivery mode. Interaction effects were evaluated using multiplicative interaction terms adjusted for gestational age and birth weight. Results Among 504 neonates, 146 (29.0%) were exposed to ACS and 247 (49.0%) developed RDS. In multivariable analysis, ACS exposure was independently associated with markedly lower odds of RDS (adjusted OR 0.243, 95% CI 0.140–0.422, P < 0.001). In subgroup analyses, the association was strongest at GA < 32 weeks (OR 0.136, 95% CI 0.044–0.415, P < 0.001) and 32–34 weeks (OR 0.223, 95% CI 0.092–0.541, P = 0.001), but was not statistically significant at 34–37 weeks (OR 0.516, 95% CI 0.259–1.029, P = 0.060). Significant interactions were observed between ACS and cesarean section (P for interaction = 0.041) and between ACS and chorioamnionitis (P for interaction = 0.030). The predictive model incorporating ACS achieved an AUC of 0.868 (95% CI 0.809–0.927). Conclusions ACS was associated with substantially lower odds of RDS, with the strongest association observed before 34 weeks gestation, although the formal test for interaction across gestational age groups did not reach statistical significance. In exploratory analyses, the association appeared to be modified by delivery mode and chorioamnionitis status. These findings support individualized, risk-stratified ACS administration rather than uniform use across all preterm gestational ages.