583 - The Timing of Antenatal Steroids and Preeclampsia Influence Respiratory Outcomes in Preterm Infants

Poster Number: 583
Publication Number: 583.3147

Background: Preeclampsia (PE) affects 25% of preterm births and is associated with increased risk of RDS and BPD in preterm infants. In PE, placental imbalance of angiogenic factors and endothelial dysfunction is associated with impaired lung vascularization and surfactant production. Antenatal steroids (ANS) enhance lung maturation but inhibit lung vascular growth. The effect of the timing of ANS administration relative to birth on the preterm infant’s respiratory course and the individual or combined effects with PE are poorly understood.

Objective: To evaluate individual and combined effects of ANS and PE on incidence of RDS and moderate-severe BPD in preterm infants.

Design/Methods: Data from a cohort of infants of 23-30w gestational age (GA) born in 2012-2021 to mothers who received ANS were analyzed. ANS was classified into 2 groups, 1)ANSbefore7d: All ANS doses administered >7d before birth and 2)ANSwithin7d: Any ANS dose administered within 7d of birth. PE was defined as new onset hypertension after 20w GA with systolic BP>140mmHg/diastolic BP>90mmHg. RDS was defined as mechanical ventilation with FiO2 ≥.30 on d1. BPD was defined per NIH consensus based on supplemental oxygen need or positive pressure ventilation at 36w PMA. Multivariate analyses were performed with generalized estimating equations, adjusted for sibling clusters and other confounders.

Results: 1172 infants were included. 28% were born to mothers with PE and 83% were born to mothers who received ANSwithin7d of birth (Table 1). Multivariate models showed ANSbefore7d and PE were independently associated with increased risk of RDS and BPD. ANSbefore7d combined with PE had a more striking risk of RDS and BPD (Figs. 1 and 2).

Conclusion(s): In this cohort of preterm infants, while ANS before 7d of birth and PE independently increased risk for RDS and BPD, the combination of both factors resulted in considerably higher risk for BPD. ANS is beneficial in improving respiratory outcome but the effect depends on timing of administration relative to birth. The impairment in lung maturation associated with PE seems to be attenuated by ANS administration within 7d of birth. These data suggest developing strategies to optimize the timing of ANS administration. Further studies should delineate the mechanisms involved in the interaction between ANS and PE on lung development in preterm infants.