Objective: To evaluate the effectiveness of antenatal corticosteroid administration in the late preterm period (34 0/7- 36 6/7 weeks of gestation).

Methods: A Medical Librarian performed a search in the following databases and grey literature sources from inception until July 15, 2024: PubMed (NLM), Embase.com (Elsevier), Scopus (Elsevier), Cochrane CENTRAL (Wiley), CINAHL Ultimate (EBSCOHost), ClinicalTrials.gov and WHO ICTRP. Methods: This study screened studies using two independent reviewers based on the predefined inclusion/exclusions criteria. This study included randomized controlled trials (RCTs) comparing antenatal corticosteroid administration with placebo or with no treatment given to individuals with singleton gestations at 34 0/7 - 36 6/7 weeks. Methods: This study appraised the included randomized controlled trials using two independent reviewers based on the Cochrane RoB 2 tool and other assessment measures. The primary outcome was the incidence of respiratory distress syndrome (RDS) (6 trials, 5163 newborns). Secondary outcomes included hypoglycemia (as defined by each trial) (4 trials, 4750 newborns), incidence of transient tachypnea of the newborn (TTN) (4 trials, 4292 newborns), neonatal intensive care unit (NICU) admission (6 trials, 5169 newborns), continuous positive airway pressure (CPAP) use for ≥2 hours (4 trials, 4760 newborns), surfactant administration (2 trials, 3100 newborns), neonatal sepsis (4 trials, 4754 newborns), neonatal mortality (5 trials, 4920 newborns), need for resuscitation in the labor suite (4 trials, 4647 newborns), hyperbilirubinemia (2 trials, 1156 newborns), necrotizing enterocolitis (NEC) (2 trials, 3710 newborns), mechanical ventilation (5 trials, 5069 newborns) and Apgar Score at 5 minutes of life (2 trials) and maternal outcomes. The summary measures were reported as relative risk (RR) or as mean difference (MD) with 95% of confidence interval (CI) using the random effects model of DerSimonian and Laird. I-squared(Higgins I2) greater than 0% was used to identify heterogeneity.

Results: Six RCTs, encompassing 5,143 deliveries, were included for analysis. The incidence of RDS was similar in the two groups (RR 1.03, 95% CI 0.73-1.45), as was the rate of transient tachypnea of the newborn (TTN) (RR 0.93, 95% CI 0.67-1.29). Antenatal corticosteroids significantly reduced the use of CPAP ≥ 2 hours (RR 0.78, 95% CI 0.65-0.94; p= 0.007) and surfactant (RR 0.61, 95% CI 0.38-0.99; p= 0.04) compared to the control. There were no significant differences in mechanical ventilation (RR 0.75, 95% CI 0.51-1.11), NICU admission rate (RR 0.94, 95% CI 0.84-1.05), hypoglycemia (RR 1.28 95% CI 0.93-1.74) neonatal death (RR 0.94, 95% CI 0.34-2.63), Apgar Score at 5 min (MD -0.07 95% CI 95% -0.17-0.03) compared between the two groups. The need for resuscitation, incidence of neonatal sepsis, hyperbilirubinemia, neonatal enterocolitis, cesarean delivery, chorioamnionitis, fever and postpartum endometritis were also similar between the two groups.

Conclusions: Antenatal corticosteroids administered between 34 0/7-36 6/7 weeks of gestation in patients at risk of preterm birth do not reduce RDS but reduce the use of CPAP for more than 2 hours and surfactant.