Abstract
OBJECTIVES: Antenatal corticosteroids (aCS) are an important measure improving the outcome of preterm infants. Their influence on late-onset sepsis (LOS) risk remains inconclusive. The alarmin S100A8/A9 protects from LOS by regulating innate immune responses. We examined whether aCS impact on postnatal S100A8/A9 serum-levels and consequently on LOS risk. STUDY DESIGN: In a prospective birth-cohort study of 162 preterm infants born before 32 gestational weeks, we determined postnatal S100A8/A9 serum-levels in relation to the timing of aCS and LOS incidence. RESULTS: aCS administration within 7 days before birth decreased LOS incidence in infants born via primary C-section compared to infants not exposed to aCS (5/69 (7.2%) vs. 4/27 (14.8%)). This effect was linked to increased S100A8/A9 levels, with nocturnal aCS administration being most effective. Opposite, S100A8/A9 levels were lower and the LOS incidence higher compared to unexposed infants (7/23 (30.4%) vs. 4/27 (14.8%)) when aCS were administered more than 14 days before delivery. CONCLUSION: Our data suggest that aCS administration affects the risk of LOS in preterm infants in dependence of the timing of administration by influencing the infant's S100A8/A9 levels. This underlines the importance of optimal timing of aCS facing imminent preterm birth.