Background: Antenatal corticosteroids (ACS) are given to pregnant women at risk of preterm delivery to hasten the maturation of the lungs, lowering the risk of newborn respiratory distress syndrome (RDS) and perinatal mortality.

Objective: The aim of this study was to determine whether exposure to ACS was associated with lower rates of perinatal mortality and RDS in preterm infants delivered by women with preterm labour.

Methods: This is a secondary analysis of data from four hospitals in Mwanza, Tanzania. All singletons and twins born to women who were in preterm labour between July 2019 and February 2020 and delivered in-hospital between 24 and 34 weeks of gestation were included. Data were recorded from participants’ medical records and analysed using STATA Version 14.

Results: Over an eight-month period, 588 preterm infants were delivered to 527 women. One hundred and ninety (36.1%) women were given ACS. Infants who were exposed to ACS in utero had a lower rate of perinatal mortality (6.8% vs 19.1%) and RDS (12.3% vs 25.9%) compared to those not exposed to ACS. In adjusted multivariable models, ACS exposure was related to a lower risk of perinatal mortality, aRR 0.23 (95% CI 0.13 - 0.39), and RDS, aRR 0.45 (95% CI 0.30 - 0.68).

Conclusion: ACS significantly reduced the risk of perinatal mortality and RDS among preterm infants exposed to ACS in utero and delivered by women in preterm labour. The use of ACS should be encouraged in low-resource settings where preterm birth is prevalent to improve perinatal outcomes.

Keywords: Antenatal corticosteroids; preterm labour; perinatal mortality.