Introduction: Preterm birth is a public health problem and late preterm birth (deliveries between 34-36 weeks of gestation) accounts for 75% of all preterm births. Antenatal Betamethasone can reduce the severity of respiratory distress in preterm infants and its effect is accepted in 24-34 weeks of gestation. Our goal was to determine the neonatal outcomes of Betamethasone prescription in late preterm births.

Materials and methods: In a prospective cohort study in a tertiary teaching hospital, the women at 34-36 weeks of gestation and at risk for imminent preterm delivery took one course of Bethametasone arbitrarily according to the on-call physician order (Betamethasone group) and the rate of neonatal respiratory distress and NICU admissions was assessed, and we compared the results with the results of late preterm deliveries without taken antenatal Betamethasone (Control group).

Results: We had 213 patients in control group and 187 in Betamethasone group. There was a significant difference between results, in two groups in 34 and 35 weeks deliveries. Frequency of need to respiratory support in Control group was 33.3% and in Betamthasone group was 9.6%. NICU admission in Control group was 33.8% and in Betamethasone group was 10.7% (P=0.00).

Discussion and conclusion: In 34 and 35 weeks of gestation, one antenatal Betamethasone course, even a single dose of Betamethasone has a significant effect on reduction of the respiratory distress and NICU admission rate.