Background: Preterm labor is the most common complication of the pregnancy in the second trimester and has been suggested as the cause of two-thirds of neonatal mortality. Antenatal corticosteroid is used for fetal lung maturity in preterm labor and makes a significant reduction in the incidence of respiratory distress syndrome (RDS). The aim of this study was to compare the prenatal administration of single and multiple courses of betamethasone and neonatal outcomes, effectiveness and safety of its weekly administration.

Materials and methods: A randomized, double-blind placebo-control clinical trial study conducted in pregnant women at risk for preterm birth by gestational age between 28 and 35 weeks. The women received a course of betamethasone at first, and then divided into a single course and multiple betamethasone courses. They evaluated for the incidence of RDS, need for oxygen, surfactant administration, the need for ventilation, duration of hospitalization and neonatal mortality. Data were analyzed using SPSS-version 16 and Chi-square test and t-test.

Results: The need for O2, the incidence of RDS, the need for hospitalization, days of hospitalization, the need for continuous positive airway pressure, ventilation and surfactant and the mortality significantly lower in the multiple course groups and betamethasone had a clear positive effect in this regard. Mean weight, height and head circumferences were significantly lower in the multiple course group.

Conclusion: Despite a positive impact of multiple betamethasone usage on mortality and morbidity in neonates, it is recommended to avoid routinely using of betamethasone multiple courses until the adequate data of studies prove the safety of reduction in weight, height, and head circumference in a long period.