Trends in receipt of single and repeat courses of antenatal corticosteroid administration among preterm and term births: A retrospective cohort study

Aim: To investigate trends in receipt and timing of antenatal corticosteroid (ACS) administration over a ten-year interval. Methods: Retrospective cohort study of all live births from 2006 to 2015 occurring at a tertiary level teaching hospital in Adelaide, Australia. We analysed temporal trends in the receipt of single courses and repeat doses of ACSs, according to administration timing prior to birth. The main outcome measures were receipt of a single course of ACS and whether administration was ‘Optimal’ (≥24 h to <seven days) or ‘Suboptimal’ (<24 h OR ≥7 days) according to timing prior to birth, as well as administration of repeat doses. Results: Among 47 105 live births, 4191 (8.9%) received any ACS, while 1009 (2.1%) received at least one repeat dose. From 2006/7 to 2014/15, receipt of a single course (relative risk (RR) 1.33; 95%CI 1.21, 1.47) or repeat dose of ACS (RR 1.24; 95%CI 1.01, 1.55) increased. Among women giving birth between 23–34 weeks gestation, receipt of any ACS increased from 75 to 84%, while an optimally timed single course of ACS increased from 20.4 to 31.0% (RR 1.40; 95%CI 1.24, 1.87). From 2006/7 to 2014/15, the greatest increase in ACS administration was evident among infants born 35–36 and ≥37 weeks gestation by caesarean section (RR 1.94; 95%CI 1.48, 2.55 and RR 2.55; 95%CI 1.86, 3.50, respectively). Conclusions: While frequently used, less than half of ACS administration prior to preterm birth was optimally timed. The impact of suboptimal ACS timing on neonatal outcomes requires further investigation.