Neonatal outcomes following antenatal corticosteroid administration before planned caesarean birth at late preterm or early term (36-38 weeks' gestation): a retrospective cohort study.

OBJECTIVE: To investigate the benefits and harms associated with antenatal corticosteroids (ACS) prior to planned caesarean birth at late preterm or early term. DESIGN: Retrospective cohort study. SETTING: South Australia, Australia, 2005-2018. PATIENTS: Women with singleton pregnancies undergoing planned caesarean birth between 36+0 and 38+6 weeks' gestation. METHODS: We used routinely collected electronic maternity and neonatal data. Adjusted risk differences (aRD) with 95% CIs were calculated for neonatal and maternal outcomes. OUTCOME MEASURES: Neonatal outcomes included respiratory distress requiring oxygen, hypoglycaemia requiring glucose, neonatal unit (NNU) admission and prolonged NNU admission (≥48 hours). RESULTS: Among the cohort of 4049 women, the proportion receiving ACS was 54.8%, 48.4% and 5.6% at 36, 37 and 38 completed weeks' gestation, respectively. ACS administration was associated with a significant reduction in respiratory distress across all gestations, with the greatest reduction seen at 36 weeks' gestation (aRD -12.5%; 95% CI -21.4% to -3.6%). At 38 weeks' gestation, ACS administration was associated with an increased risk of neonatal hypoglycaemia (aRD 5.7%; 95% CI 1.1% to 10.2%), NNU admission (aRD 5.4%; 95% CI 0.1% to 10.7%) and prolonged NNU admission (aRD 4.6%; 95% CI 0.2% to 8.9%). CONCLUSIONS: ACS administration prior to late preterm and early term planned caesarean birth was associated with reduced risk of respiratory distress. The net benefit of ACS administration before planned caesarean birth remains unclear; however, there was evidence of potential neonatal harm when birth occurred after 37 weeks' gestation.